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UNIVERSITY  OF  ILLINOIS 
LIBRARY 


Class  Book  Volume 


My  08-1 5M 


The  person  charging  this  material  is  re- 
sponsible for  its  return  on  or  before  the 
Latest  Date  stamped  below. 

Theft,  mutilation,  and  underlining  of  books 
are  reasons  for  disciplinary  action  and  may 
result  in  dismissal  from  the  University. 

University  of  Illinois  Library 


OCT  2  0  1961 

?ftw  '>^  RFC* 


L161— O-1096 


.IBRARY 

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Electric  Railways 


A   Treatise  on   the 

ON,   INC 


MODERN    DEVELOPMENT    OF    ELRCTRIC  TRACTION,    INCLUDING   PRACTICAL 
INSTRUCTION     IN     THE     LATENT    'A!1'T'!>;0VKI)     METHODS 


OF  ELECTRIC    RAILROAD    R<JUIi•^tE^•T 
AND      OPERATION 


ELECTRIC    RAILWAYS 

By  James  K.   Cravath 
Western  Editor  "  The  Street  Railway  Journal  " 


THE    SINGLE-PHASE    ELECTRIC    RAILWAY 

By  Harris  C.  Trow,  S.B. 

American  InEtitnte  of  Electrical  Engineers.     Editor  Textbook  Department, 
American  School  of  Correspondence 


ILLUSTRATED 


CHICAGO 

AMERICAN    SCHOOL  OF   CORRESPONDENCE 

190  8 


bi 


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COPYRIGHT   J907   BY 
AmEP-ICAN    ScHOOI.   of   COKRESrONDENCE 


Entered  :it  Stationers'  Hall.  Ivoiuion 
All  Rig-hts  Reserved 


Foreword 


X  ivceiit  years,  sueli  luurvelous  advances  have  been 
made  in  the  engineering  and  scientific  fields,  and 
so  rapid  has  been  the  evolution  of  luechanieal  and 
constructive  processes  and  methods,  that  a  distinct 
need  has  Ijeen  created  for  a  series  of  practical 
loorlxlixj  (jaldcs,  of  convenient  size  and  low  cost,  embodying  the 
accumulated  results  of  experience  and  the  most  approved  modern 
practice  along  a  great  variety  of  lines.  To  fill  this  acknowledged 
need,  is  the  special  purpose  of  the  series  of  handbooks  to  which 
this  volume  belongs. 

C  111  the  preparation  of  this  series,  it  has  been  the  aim  of  the  pub- 
lishers to  lay  special  stress  on  the  practical  side  of  each  subject, 
as  distinu-uished  from  mere  theoretical  or  academic  discussion. 
Each  volume  is  written  by  a  well-known  expert  of  acknowledged 
authority  in  his  special  line,  and  is  based  on  a  most  careful  study 
of  practical  needs  and  up-to-date  methods  as  developed  under  the 
conditions  of  actual  practice  in  the  field,  the  shop,  the  mill,  the 
power  house,  the  drafting  room,  the  engine  room,  etc. 


C  These  volumes  are  es|M:'cially  adapted  for  purposes  of  self- 
instruction  and  home  study.  The  utmost  care  has  been  used  to 
bring  the  treatment  of  each   s\d)ject  within  the  range  of  the  com- 


111205 


iiion  understanding,  so  that  the  ^vork  will  appeal  not  only  to  the 
technically  trained  expert,  but  also  to  the  beginner  and  the  self- 
taught  ])ractical  man  who  wishes  to  keep  abreast  of  modern 
progress.  The  language  is  simple  and  clear;  heavy  technical  terms 
and  the  formuhv  of  the  hiiiher  mathematics  have  been  avoided, 
yet  without  sacrificing  any  of  the  re(][uirements  of  j)ractical 
instruction;  the  arrangement  of  matter  is  such  as  to  carry  the 
reader  along  by  easy  steps  to  complete  mastery  of  each  subject; 
frequent  examples  for  practice  are  given,  to  enable  the  reader  to 
test  his  knowledge  and  make  it  a  permanent  possession;  and  the 
illustrations  are  selected  with  the  greatest  care  to  supplement  and 
make  clear  the  references  in  the  text. 

d.  The  method  adopted  in  the  preparation  of  these  volumes  is  that 
which  the  American  School  of  Correspondence  has  developed  and 
employed  so  successfully  for  many  years.  It  is  not  an  experiment, 
but  has  stood  the  severest  of  all  tests — that  of  practical  use — which 
has  demonstrated  it  to  be  the  best  method  yet  devised  for  the 
education  of  the  busy  working  man. 

C  I'or  purposes  of  ready  reference  and  timely  information  when 
needed,  it  is  believed  that  this  series  of  handbooks  will  be  found  to 
meet  every  requirement. 


Table    of    Contents 


Car  Equipment Page   3 

Classiflc?ation  of  Electric  Uailwajs — Motors^ — Armature  ^Yinding■— 
Armature  and  Field  Coils — Armature  and  Motor  Leads — Brushes  and 
Brush- Holders — Gearing' — Lubrication — Bearing's — Motor  Suspension — 
Klectric  Locomotive  Motors — Controllers — Rheostat  and  Series-Par- 
allel Control  —  Controller  Construction  —  Multiple-Unit  Control 
(Sprague,  General  Electric,  Westinghouse  Electro-Pneumatic) — Car- 
Heaters — Car  Wiring — Electric-Car  Accessories  (Canopy  Switches; 
Circuit-Breakers;  Fuses;  Lightning  Arresters;  Lamp  Circuits;  Trolley- 
Base;  Trolley-Poles,  AVheels,  and  Harp;  Contact  Shoes;  Sleet  Wheels) 
— Single  Trucks — Swivel  Trucks — Maximum  -  Traction  Trucks  —  Car 
AVheels — Brake  Rigging — Air-Brakes  (Compressor,  Automatic  Gover- 
nor, Storage  Tanks) — Momentum  Brakes — G.  E. Electric  Brake — West- 
inghouse Electromagnetic  Brake — Track  Brakes — Motors  as  Emer- 
gency Brakes — Brake  Shoes — Track  Sanders — Drawbars  and  Couplers. 

Car  Construction Page  67 

Car    Bodies — Steel    Car    l'"r;uning — Car    Weights — Car    Painting. 

Line  Construction Page  73 

Overhead  Construction — Trcjlley-Wire — Clamps  and  Ears — Span 
Wires — Brackets — Feeders — Section  Insulators — Higli-Tcnsion  Lines — 
Third-Rail  System — Conduit  Systems — Contact  Plow — Current  Leak- 
age— Track  Construction — Girder  Rail — Trilby  Groove  Rail — Shanghai 
T-Rail — Common  T-Rail — Track  Supnort — Ballast— Joints  (Welded, 
Cast-Welded,  Electrically  Welded,  Tliermit-Welded) — Bonding  and 
Return  Circuits — Feeder  Systems — ^Block  Signals — Electrolysis  and  Its 
Prevention. 


Power  Supply  and  Distribution Page  98 

Direct-Current  Feeding  —  Booster  Feeding  —  Al  t<'rnatinff-Current 
Transmission  —  Interurban  Distribution  —  Power-House  Location — 
Alternating-Current  Generators — Double-Current  Generators — Gen- 
eral Plan  of  Power  Stations — Switchboards — Generator  D.  C.  Panels — 
Starting  Up  a  Generator — Feeder  Panel — Alternating-Current  Switch- 
boards— High-Tension  Oil-Switches — Storage  Batteries  in  Stations — 
Three-Phase  Motors — Single-Phase  Motors. 

Operation  of  Electric  Railways Page  115 

Power  Taken  by  Cars — Road  Tests  of  Cars — Economy  in  Power — 
Sliding  and  Spinning  \A  heels — Testing  for.  Faults — Bond  Testing — 
Motor-Coil  Testing — -Grounds  —  Burn-Outs  —  Defects  of  Armature 
Windings — Sparking  at  Commutatoi' — Failure  of  Car  to  Start — Open- 
Circuit  Tests — Short-Circuit  Tests — Fuse-Blows — Armature  and  Field 
Tests  for  Grounds — Reversed  Fields — Car  Repair  Shops. 

The  Single-Phase  Electric  Railway ,      .  Page  137 

Commutator  Type  Single-Phase  Motor — Advantages  and  Disadvan- 
tages of  .Single-Phase  System — Lines  in  Operation. 

Index Page  149 


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ELECTRIC  RAILWAYS, 

PART  I. 


The  general  name  "electric  railway"  is  applied  to  all  railways 
employing  electric  motors  to  supply  power  for  the  propulsion  of  cars. 
On  all  electric  railways  in  commercial  use  to-day,  the  electric  motor 
is  used  to  furnish  power  to  the  driving  wheels  of  the  car  or  locomotive, 
the  electric  motor  being  the  most  efficient  known  means  of  transform- 
ing electrical  into  mechanical  energy. 

Electric  railways  are  usually  classified  according  to  the  methods 
by  which  current  is  supplied  to  the  moving  car.  Thus,  where  an 
overhead  trolley  wire  is  used,  as  on  the  great  majority  of  electric  rail- 
ways, the  term  trolley  road  is  applied.  Where  an  insulated  steel  rail 
is  laid  alongside  the  track  rail  for  supplying  current,  as  on  the  "e:e- 
vated"  roads  in  America  and  on  a  few  interurban  roads,  the  term 
third-rail  road  is  used.  Where,  as  on  the  street  railways  of  a  few 
large  cities,  the  conductors  are  })laced  in  a  conduit  underneath  the 
surface  of  the  street,  and  current  is  taken  l)y  means  of  a  plow  or  shoe 
running  in  the  conduit,  the  name  electric-conduit  railway  is  most  com- 
monly applied.  There  are  also  a  few  systems  using  conductors  buried 
beneath  the  pavement,  and  having  contact  buttons  or  sections  of 
conductor  rail  on  the  street  surface,  which  sections  are  supplied  with 
current  by  automatic  electromagnetic  switching  apparatus  as  the 
car  passes,  but  which  are  normally  dead  and  harmless.  The  over- 
head trolley  and  the  third-rail  systems  are  by  far  the  most  common. 

A  further  general  classification  of  electric  railways  has  recently 
been  made  because  of  the  introduction  of  alternating-current  railway 
motors.  The  great  majority  of  electric  railways  em{)loy  direct- 
current  motors.  Wliere  alternating-current  motors  are  used,  the 
ro.ad  is  sp(jkeii  of  as  one  using  single-phase  alternating-current  motors 
or  three-phase  alternating-current  motors,  as  the  case  may  be. 

All  electric  railway  systems  in  commercud  use  are  operated 
on  an  approximately  constant  j)otential  ur  voltage,  and  the  various 
electric  motor  cars  operating  on   tlu>  system   are  c(mnected   across 


ELECTRIC    RAILWAYS 


the  lines  in  parallel.  The  most  coniuion  practice  is  to  utilize  the 
rails  and  ground  as  one  side  of  the  circuit,  and  the  overhead  trolley 
wire  or  "third  rail"  as  the  other  siile,  as  in  Fig.  1.  The  trolley  wire 
or  third  rail  is,  of  course,  thoroughly  insulated  from  the  ground. 
The  positive  poles  of  the  generators  at  the  j)o\ver  house  are  usually 


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connected  to  the  trolley  wire,  and  tlie  r.egative  ]K)les  to  the  rails 
and  ground.  The  various  electric  motor  cars,  heing  connected  in 
parallel  or  multiple  between  the  trolley  wire  and  the  ground,  draw 
whatever  current  is  necessary  for  their  operation.  Where  the  conduit 
system  is  used,  both  sides  of  the  circuit  are  insulated  from  the  ground, 
and  the  contact  shoe  or  plow  collects  current  from  two  conducting 
rails  in  the  conduit,  one  of  these  conducting  rails  being  positive  and 


Fig.  2.     ]i:iiUvay  Motor. 


the  other  negative.  A  double-trollev  svsteni  is  also  in  use  to  a  limited 
extent.  In  this  system,  both  the  positive  and  the  negative  sides  of 
the  circuit  are  msulated  from  the  ground,  one  trolley  wire  being 
positive  and  the  other  negative. 

Further  discussion   of  \\w  matters  just   outlined   will   be  taken 
up  in  the  succeeding  pages. 


ELECTRIC    RAILWAYS 


CAR  EQUIPHENT. 
MOTORS. 

The  voltage  most  commonly  employed  by  electric  railways  is 
500  to  600;  and  the  motors  are  500-volt  direct-current  series-wound 
motors,  designed  especially  for  railway  service.  The  electric  railway 
motor  must  he  dustproof  and  waterproof  because  of  the  position  it 
occupies  under  the  car.  For  this  reason  electric  railway  motors  are 
made  in  the  form  of  a  steel  case  (Fig.  2),  which  entirely  surrounds 
the  field-magnet  poles  and  takes  the  place  of  the  yokes  or  frames 
that  support  the  fields  on  stationary  motors.  Cast  steel  is  the  material 
now  usually  employed  for  railway  motor  cases  and  fields,  on  account 


Fig.  3.    Kailway  Motor.    Upper  Field  Kaised. 


of  its  mechanical  strength  and  its  high  magnetic  permeability.  The 
four  poles  project  inwardly  from  the  case,  as  seen  in  the  open  motor 
case,  Fig.  3,  which  is  that  of  a  Westinghouse  No.  G9  motor. 

Railway  motors  have  usually  four  poles  because  this  permits 
:)f  a  symmetrical  and  economical  arrangement  of  material  around 
the  armature,  and  hence  permits  the  motor  to  be  placed  in  the  small 
space  available  on  the  car  truck.  Two-pole  motors  have  been  used 
in  the  past,  but  they  were  not  as  compact  as  the  foiu'-pole  type 

Characteristics  of  Railway  Motors.  The  curve  sheet,  Fig. 
4,  for  the  Westinghouse  No.  69  motor  represents  in  general  the  char- 
acteristics of  all  direct-current  railway  motors. 

The  figures  for  each  curve  are  found  with  luunes  corresponding 
to  the  curve  to  which  they  apj)ly,at  each  side  represented  by  vertical 


ELECTKIC    RAILWAYS 


(listanc'f  dh  the  slieet.  The  ainjxTes,  ivpreseiited  bv  the  horizontal 
(Hstance,  are  marked  at  the  bottom,  and  apply  in  common  to  all  the 
cur^'es. 

The  tractive  effort  at  different  current  consumption  is  represented 
l)v  a  line  curvin<;  upwards  somewhat.  I'his  shows  that  the  tractive 
effort  increases,  in  a  proportion  greater  than  directly,  as  the  current 
increases. 

The  tonjue  recpiired  in  starting  may  be  many  times  greater  than 
that  necessary  to  maintain  the  car  at  full  speed.     The  series-wound 


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WESTINGHOUSE 

No.69  RAILWAY   MOTOR 

500  VOLTS 

GEAR  RATIO.  14  TO  68.         WHEELS.  33  " 

CONTINUOUS  CAPACITY,   2S  AMPERES  AT  300  VOLTS, 

OR  23  AMPERES  AT  400  VOLTS. 

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Fi? .  4.    Characteristic  Curves  of  Railway  Motor. 

motor,  therefore,  furni.shes  this  great  .starting  torcjue  more  economically 
than  a  .shunt-wound  motor  the  tonpie  of  which  is  projM)rtionc<l  to  tiic 
•  iirrent.  This  feature  of  the  .series-woimd  motor  makes  it  especially 
adapted  to  .street  railway  work. 

The  efficiency  curve  .shows  the  motor  to  have  an  efficiency  of 
about  S3  per  cent  with  gears.  Much  other  infon^iation  may  be 
obtaint^l  bv  a  proj>er  study  of  the  curves. 


ELECTRIC    RAILWAYS 


5 


The  fields  are  worked  near  the  ])oint  of  niaji;netic  saturation. 
This  economizes  metal  and  space  and  is  also  an  advantage  because 
of. the  fact  that  when  so  worked  the  armature  reactions  have  verv 
little  eli'ect  on  the  fields.  'I'he  neutral  j)()int.>+  between  fields  are 
consequently  shifted  very  little  and  it  is  therefore  not  necessarv  to 
shift  the  brushes  when  the  motor  is  reversed. 

Armature  Winding.  'J'he  armature  v^.!  :<ling  is  what  is  com- 
monly known  as  the  series  or  wave  winding,  shown  develo})ed  in 
the  paper  on  Direct-Current  Dyna- 
mos. This  winding  is  shown  in 
Fig.  5,  which  is  an  end  view  of  an 
armature  and  commutator.  In  the 
figure,  however,  the  armature  is 
shown  with  a  much  smaller  number 
of  slots  than  a  raihvav  armature 
shoidd  have  in  practice.  One  reason 
for  the  emplovment  of  the  wave  or 
.series  winding  on  railway  motor 
armatures,   is  that   with   this  wind- 


mg  no  cross-connections  are  neces- 


Fij,'.  5.     Aniiatuvr  Winding. 


sary  when  only  two  brushes  ai'e 
used,  and  these  two  brushes  may  be  placed  00°  apart  in  a  convenient 
and  acce.ssible  position.  Another  reason  is  that  the  current,  in  flow- 
ing from  one  brush  on  the  commutator  to  another,  must  always  pass 
through  the  magnetic  field  of  all  four  of  the  motor  poles.  This  makes 
it  impossible  for  any  unbalancing  of  the  magnetic  circuit  to  cause  more 
current  to  flow  through  one  portion  of  the  armature  than  is  flowing 
through  another  jiortion.  In  a  railway  motor  it  has  been  found  quite 
possible  to  have  one  pole  or  j^air  of  poles  exerting  a  greater  magnetic 
attraction  on  the  armature  than  another  j)air,  owing  to  diflerences  in 
the  iron  and  diflerences  in  the  clearance  between  the  armature  and 
pole  pieces,  which  diflerences  cau.se  more  magnetic  lines  of  force  to 
flow  from  some  pole  pieces  than  from  others.  With  the  lap-armature 
or  the  ring-armature  winding,  since  the  various  portions  of  the 
armature  under  ditt'erent  poles  are  in  parallel  with  one  another,  any 
difl'erence  in  the  magnetic  flux  betvv'een  diflerent  ])oles  will  cause  a 
difl'erent  amount  of  current  to  (low  in  the  various  paths  through  the 
armature. 


6 


ELECTRIC    KAILWAYS 


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ELECTRIC    RAILWAYS 


By  reference  to  tlie  windiiif];  diagram  given  in  Fig.  5,  it  may  be 
noted  that  a  complete  circuit  through  two  coils  ends  at  the  seg- 
ment adjacent  to  the  one  from  which  the  start  was  made.  It  may 
also  be  noted  in  the  table  of  motor  data  that  all  of  the  armatures 
have  an  odd  nimiber  of  segments  and  an  odd  number  of  slots.  It 
is  absolutelv  necessarv  in  a  wave  windin«jj  to  have  an  odd  number- 
of  segments.  Otherwise  the  winding  could  not  be  made  symmetrical 
and  the  circuit  through  two  coils  be  made  to  return  to  a  segment 
adjacent  to  that  from  which  the  start  was  made.  ^Yith  equal  spacing 
between  the  top  and  bottom  leads  of  the  two  coils,  an  even  number 
of  segments  would  make  the  circuit  return  either  on  the  segment 
from  which  the  start  was  made  or  two  segments  from  it. 

The  first  drum-wound  street  railwav  motor  armatures  had  as 
many  slots  in  the  armature  as  there  were  coils  and  segments.  The 
great  number  of  slots  necessarily  made  the  teeth  very  thin  and  con- 
secpiently  weak.  This  is  very  objectionable  as  sometimes  the  arma- 
ture bearings  wear  away,  allowing  the  face  of  the  armature  to  drag 
on  the  pole  pieces  and  thin  teeth  are  bent  out  of  shape. 

Armatures  are  now  almost  entirely  constructed  with  either  two 
or  three  coils  to  a  slot.  When  two  coils  are  used  in  each  slot  with 
an  odd  number  of  slots  an  even  number  of  coils  results.  If  these  were 
all  connected  to  the  commutator  an  even  number  of  segments  would 
be  necessary.  As  this  is  not  possible  with  a  wave  winding,  one  of 
the  coils  is  "cut  out."  The  ends  are  cut  short  and  taped  and  it  is 
termed  a  "dead"  coil.  This  makes  the  winding  somewhat  unsym- 
metrical,  all  the  coils  not  bearing  the  same  angular  relation  to  the 
commutator  segments  to  which  they  are  connected.  This  difference 
is,  however,  not  great  enough  to  affect  the  operation  of  the  machine. 

The  Westinghouse  49  motor  is  an  example  of  an  armature  with 
a  dead  coil.  By  reference  to  the  table  of  motor  data  it  will  be  seen 
that  this  armature  has  59  slots.  Two  coils  in  each  slot  would  make 
118  coils.     One  of  these,  however,  is  cut  out,  giving  117  segments. 

Cutting  out  a  coil  can  be  avoided  by  putting  three  coils  in  each 
slot. 

An  odd  number  of  coils  results  then  no  matter  what  the  number 
of  slots  may  be.  In  the  majority  of  examples  given  in  the  table 
there  are  three  times  as  many  segments  as  slots. 


8  •  ELECTRIC    RAILWAYS 


The  sides  of  the  slots  of  modern  street  railway  armatures  are 
strai<;ht.  Tlie  coils  are  prevented  from  Hyinfj  out  l)y  l)ands  of  wire 
extendiufj;  over  the  tops  of  the  coils  around  the  armature.  Steel 
or  silicon  bronze  wire  of  about  No.  14  gauge  is  used.  Recesses  are 
made  in  the  armature  teeth  for  the  reception  of  these  bands  so  that 
the  wire  when  womid  will  come  flush  with  the  face  of  the  armatiu'e. 
The  bands  are  usually  4  to  1  \  inches  wide.  The  wires  are  well 
soldered  together  to  secure  them  in  ])lace.  One  trouble  experienced 
with  armatures  is  the  slipping  off  of  these  bands.  The  heated 
armature  expands  and   stretches  them.     ^Vhen   the  armature  cools 


^^^^ 


Fig.  C).     ArnKitnvf  ( 'oil. 

the  bands  are  loose  and  then  often  slip  off.  "When  they  do  so  the 
coils  lly  out  by  centrifugal  force,  strike  the  pole  pieces  and  groimd 
the  motor. 

Armature  Coils.  Railway  motor  armatures  are  to-day  imi- 
versally  constructed  with  form-wound  coils,  wiiich  are  wound  on 
a  form  of  proper  shape  and  carefully  insulated  before  l)eing  placed 
in  the  armature. 

The  coils  of  the  smaller  motors  (those  \\\)  to  40  or  .')()  h()rsej)ower) 
are  usuallv  wound  with  round  wire.  'I'he  cotton  covering  of  the  wire 
is  de])ended  u])on  for  insulation  To  strengthen  this,  however,  t!ie 
coils  after  being  wound  are  immersed  in  an  insulating  compoimd 
and  then  baked  in  an  oven.  The  whole  coil  is  usually  wrapped  with 
insulating  tape  (See  Fig.  (>).  The  armatures  of  larger  motors  have 
coils  made  of  copper  bars.  Mica  is  often  placed  between  and  around 
the  bars  for  insulation,  though  oiled  linen  cloth  tape  cut  bias  is  also 
employed,  especially  in  repair  work. 

Field  Coils.  Field  coils  are  so  constructed  that  they  may 
be  readily  removed  should  they  become  grounded  or  .short-circuited. 


ELECTRIC    KAILWAWS 


Some  niiikers  wind  tlieiii  on  a  l)rass  shell  or  form  which  is  slipped 
over  the  ])ole  j)ie(e.  In  some  motors  the  field  eoils  are  composed 
of  copper  rih!)on,  wound  hare,  with  rihhons  of  insulatin<j;  material 
between  the  turns.  Field  coils  of  wire  for  the  smaller  motors,  if  not 
» wound  on  shells,  are  wound  on  forms  and  before  completion  are 
taped  in  such  a  manner  that  they  will  hold  their  shape  without  being 
enclosed  in  a  spool.  The  termi- 
nals are  brought  out  where  thev 
will  be  of  easy  access  when  the 
field  is  in  place  (See  Fig.  7). 

Armature  Leads.  In  Fig. 
3  is  seen  a  completed  armature 
in  the  motor  casing  of  a  Westing- 
house  No.  69  motor.  Since  the 
motors  are  foin-pole,  the  two  sides 
of  any  one  coil  occupy  slots  !)()° 
apart  in  the  armature  coil,  as  in- 
dicated in  Fig. .').  The  ends  of  the 
coils  are  connected  to  commutator 
l)ars  LSO°  apart.  The  relative 
])osition  of  the  commutator  con- 
nections of  any  armature  coil  can, 
of  cour.se,  be  varied  so  as  to  bring 

the  brushes  in  the  mo.st  convenient  position  in  the  motor  casing. 
Brushes  are  always  of  carbon,  and  are  placed  where  they  can  be  easily 
reached  from  the  opening  in  the  motor  casing  over  the  commutator. 

Motor  Leads.  The  reversing  of  the  current  through  the 
armature,  independent  of  the  field  current,  to  secure  reversal  of 
direction  of  rotation  of  the  armature,  makes  it  necessary  that  four 
wires  enter  the  motor.  The  portions  of  these  wires  connected  per- 
manently to  the  motor  are  termed  the  motor  leads  because  they 
"lead  out"  the  current.  Sometimes  an  ordinary  two-way  connector 
is  used  in  connecting  these  leads  to  the  wires  of  the  cable,  but  often 
a  jack-knife  connector  is  employed  to  facilitate  connecting  and  dis- 
connecting. Considerable  difficulty  has  been  experienced  by  the 
wearing  away  of  the  insulation  of  the  leads  where  they  rest  on  the 
motor  shell.  To  avoid  this  there  has  recently  come  into  use  a  lead 
protected  by  a  spiral  metal  covering. 


Fig.  ■ 


Field  C.)il. 


10 


E  L EOT RIC    K A  T  I. \V A YS 


Brushes.  That  the  motor  may  operate  in  either  direction 
e(iually  well,  the  carbon  hrushes  are  placed  radially  or  nearly  so. 
No  provision  is  made  for  shifting  their  position  relative  to  the  fields. 
They  nsually  occupy  a  position  erpiidistant  between  pole  tips. 
The  connnoii  types  are  either  ^  or  f-inch  thick  and  from  2}  to  4 
inches  wide. 

Brush  Holders.  Two  methods  of  securing  the  brush  holders 
arc  employed.  In  Fig.  3,  the  brush  holders  may  l)e  seen  to  be 
secured  in  position  by  being  bolted  through  the  end  of  the  motor 
shell.     Fig.  S  shows  the  brushes  mounted  on  a  yoke  which  is  secured 

to  the  motor  shell.  The  yoke  is  of  wood  and 
provides  the  necessary  insulation.  Where  the 
holders  are  fastened  directly  to  the  shell  a 
block  and  washers  of  vulcabeston  or  other 
insulating  material  intervene  to  furnish  the 
insulation  between  the  shell  and  the  holder. 
In  practice  the  greatest  difhculty  experi- 
enced with  brush  holders  is  preventing 
them  from  becoming  grounded  by  dirt  and 
carbon  dust  which  collects  on  the  insulation. 
Opening  Cases  for  Inspection.  Accessibility  for  inspection 
and  re])airs  is  essential  in  all  railway  motors.  A  lid  is  always  ])ro- 
vided  directly  over  the  commutator  to  facilitate  inspection  of  the 
commutator  and  brushes.  To  open  up  the  motor  casing  for  more 
extensive  inspection  or  repairs,  three  general  schemes  are  emploved. 
One  is  to  have  the  lower  half  of  the  casing  swing  downward  on  a 
hinge  as  in  Fig.  9,  which  illustrates  the  Westinghouse  No.  .3.S  B 
motor.  The  armature  may  be  placed  either  in  the  lower  half,  as 
shown  in  Fig.  0,  or  in  the  upjier  half.  When  a  motor  of  this  type  is 
to  be  ()j)cncd  th<'  car  is  run  over  a  j)it,  and  the  rej)air  men  work 
entirely  from  below. 

Often  the  hinge  pins  are  removed  and  the  lower  shell  containing 

the  armature  is  dro])])ed  down  by  means  of  a  jack  placed  underneath. 

Two   handholes   are   usually  provided  in  the   bottom  shell  for 

observing  the  clearance  between  the  armature  and  the  j)(;le  pieces 

ahd  also  for  removing  dirt  that  mav  collect  in  the  bottom  of  the  shell. 


Fig.  8.     nrnsh  Holder. 


ELECTKIC    RAILWAYS 


11 


Another  sclioiiie  is  to  liavo  motors  o|)oii  from  tlie  top,  either 
by  hin<:;iiifjj  the  upper  j)art  of  the  motor  easing-,  as  iii  Fi<;-.  .1,  or  l)y 
liavinjr  the  to])  part  of  the  rasing  lift  off.  \Vhere  this  form  of  motor 
is  used,  the  car  l)0(ly  is  hoisted  clear  of  the  truck,  and  the  trucks  are 
run  out  from  under  the  car  body  before  work  is  done  on  the  motors. 
In  this  case,  all  the  work  can  be  done  from  above  without  the  use 
of  pits. 

A  third  design  is  the  box-frame  motor  casing,  from  which  the 
armature  can  be  removed  endwise  only.     Such  an  arrangement  is 


Fig.  9.    Railway  Motor.    Lower  Half  of  Casing  Swung  Down. 


.shown  in  Fig.  10,  which  is  a  view  of  a  No.  GG  motor  of  the  General 
Electric  Company.  In  this  motor  a  sufficiently  large  opening  is 
provided  in  the  ends  of  the  motor  casing  to  permit  of  the  armature 
l)eing  removed  endwise.  A  plate  or  head,  which  accurately  fits 
into  this  opening,  carries  the  armature  Ijearing.  In  removing  arma- 
tures from  mfjtors  of  this  kind,  the  usual  method  is  to  take  the  motor 
out  of  the  trucks  and  .stand  it  on  end  with  the  pinion  up.  The  bolts 
being  removed  from  the  end  plate,  the  armature  can  then  be  hoisted 
out  of  the  case  by  means  of  a  special  hook  attached  to  the  pinion. 
Another  plan  that  has  been  used  in  removing  armatures  from  such 
motors,  is  to  place  the  motor  in  an  apparatus  where  the  armature 
shaft  can  ])e  held  between  centers,  as  in  a  large  lathe.     The  motor 


12  ELECTKIC    RAILWAYS 

fiisiiitf  is  then  moved  aloii<;  in  a  direction  parallel  to  the  armature 
shaft,  until  the  arnuiture  is  ex])osed. 

This  latter  hox-frame  tyj)e  of  motor  is  very  compact;  a  stron^^er 
casm<;  can  he  made  for  a  <;iven  \vei<jht  and  space  than  if  it  were 
divided  horizontally.  Moreover,  the  magnetic  circuit  cannot  he 
disturbed  l»y  imperfect  contact  hetween  two  parts  of  the  casing;. 
Where  this  type  of  motor  is  used,  the  hearings  project  inward  under 
the  commutator  and  arnuiture,  thus  getting  long  l)earings  with  a 
short  motor,  which  is  important  where  the  room  is  limited,  as,  for 
example,  in  the  case  of  a  large  motor  mounted  on  a  standard-gauge 
truck. 


Fit:.  M.     Uox-Framu  Motor. 


Gearing.  In  most  cases,  spur  gearing  is  used  to  tran.smit  power 
from  the  armature  shaft  to  the  car  axle,  although  a  few  motors  with 
armatures  mouiTted  directly  on  the  car  axle  are  in  use.  Varioiis  war- 
ings  other  than  the  simple  spur  gear  have  l)een  tried,  such  as  worm 
gears,  chain  and  V)evel  gears.  Practically  all  have  been  abandoned 
in  favor  of  the  single-reduction  spur  gearing,  -whidi  is  the  most  .satis- 
factorv  from  the  standpoint  of  wear  and  eflficiency.  This  gearing 
is  shown  in  Figs.  3  and  0.  The  gearing  is  covered  with  a  gear  case 
(Fig.  9),  which  is  usually  of  steel,  though  gear  cases  of  thin  sheet 
metal  and  wood  are  sometimes  used.  A  solid  gear  is  shown  in  Fig.  1 1 , 
and  a  .split  gear  in  Fig.  12. 


ELECTKIC    KAILWAVS 


1.'} 


The  jfear  ratios  in  coiniiion  use  vary  from  5  to  1  to  2  to  1,  the 
hirger  ratio  being  common  on  the  smaller  motors.  A  ratio  often 
used  on  motors  of  30  to  50  horsepower  is  4.7.S  to  1,  the  gear  having 
C)7  teeth,  the  pinion  14  teeth. 

Street  car  wheels  are  usually  33  inches  in  diameter.  Tliis  makes 
necessary  C12  revolutions  per  mile.  ^Vith  a  gear  ratio  of  4.7S  the 
armature  revolves  2,925  times  per  mile.  At  15  miles  per  hour,  this 
gives  731  r.p.m. 

Lubrication.  The  lubrication  of  railway  motors  was  for  a 
number  of  vears  carried  on  almost  exclusively  with  grease,  which 


Fig.  11.    Solid  Clear. 


Fig.  12.     Split  (Jear. 


it  was  customary  to  })lace  in  the  gear  casing  and  in  grease  boxes 
over  the  armature  and  car-axle  l)earings.  (Irease  becomes  most 
efficient  as  a  lubricant  only  when  the  bearing  is  heated  sufficiently 
to  make  the  grease  run  like  oil.  Oil  is  now  being  used  to  a  con- 
siderable extent,  especially  for  larger  motors.  It  is  fed  to  the  bear- 
ings by  various  devices  that  allow  a  very  slow  feed,  such  as  wicks 
and  lul)ricators  adju,ste<l  to  pass  a  .small  amount  of  oil  per  hour. 

Bearings.  Railway  motor  bearings  are  usually  of  Babbitt 
netal,  which  metal  is  cast  into  a  steel  .shell.  This  shell  fits  into 
receptacles  in  the  motor  casing,  which  can  be  seen  in  Figs.  3  and  9. 
A  steel  shell  is  used  so  that  the  worn-out  bearings  can  be  easily 
renewed  and  the  .shells  taken  to  a  Babbitt  melting  furnace  to  have 
U'jw  Bahbitt  ])()iired  into  thcm.- 

'i'he  motor  has  two  .sets  of  bearings,  those  for  the  armature  and 
tho.se  for  the  axle  upon  which  the  motor  is  mounted.  The  axle 
bearinirs  are  alwavs  ,si)lit  diametricallv  to  avoid   removing  a  wheel 


14 


ELECTRIC    RAILWAYS 


when  a  l)carin<j;  is  repUifed.  On  tlie  Inter  designs  of  motors  these 
are  of  brass,  no  Babbitt  metal  being  nsed.  The  armatnre  bearings 
are  distingnished  by  the  terms  "gear  end"  and  "commntator  end" 
bearings.  The  gear  end  bearing  is  nsnally  of  larger  diameter  and 
of  greater  length  because  of  the  thrust  of  the  gears  it  must  take  in 
addition  to  the  weight  of  the  armature.  This  bearing  is  .split  .so 
that  it  may  be  removed  and  replac-ed  without  the  removal  of  the 
gear.  The  commutator  end  bearing  is  in  one  piece.  Armatufe 
bearings  are  shown  in  Fig.  13. 


I•'il,^  Ki.     AriiKiiiirf  15carinji>i- 


riotor  Suspension,  'J'wo  methods  (;f  suspending  motors  flex- 
ibly on  trucks  are  in  common  use.  That  end  of  the  motor  which 
has  bearings  on  the  car  axle  cannot,  of  cour.se,  be,  flexibly  suspended 
with  regard  to  the  axle;  but  the  other  end  of  the  motor  can  be  placed 
on  springs,  or  re.st  on  a  bar  suj)ported  on  sj)rings,  as  .shown  in  Fig. 
14.  This  suspension  is  commonly  called  no.sc  .su.spen.s'tofi.  Instead 
of  having  a  special  bar  and  special  s])rings  for  the  nose  of  the  motor, 
the  nose  ni ay  rest  upon  some  part  of  the  truck  that  is  carried  upon 
springs.  Thus,  on  the  IVI.  C.  B.  type  of  swivel  truck,  the  nose 
usually  rests  on  the  truck  bolster,  and  thus  gets  the  benefit  both  of 
the  bolster  .springs  and  of  the  ecpiali'/er  .springs  of  the  truck.  Another 
general  ])lan  of  suspension  is  that  known  in  one  form  as  cradle  -fus- 
'pensicm,  and  in  another  form  as  sidc-lxir  suspension.  A  si(le-l)ar 
suspension  is  shown  in  Fig.  1").  Here  a  larger  percentage  of  the 
weight  of  the  motor  is  evidently  taken  by  the  s])rings  than  in  the 
case  of  nose  suspension.      It  is  desiral)li>  to  relieve  the  car  axle  of  as 


ELECTRIC    RAILWAYS 


15 


much  dead  weight  as  possible.     By  dead  weight  is  meant  weight 
resting  upon  it  without  the  intervention  of  springs. 

Motors    of    the    New    York    Central    Electric    Locomotive. 
These  motors  are  a  radical  departure  from  the  usual  type  of  rail- 


■  ''^ 

, 

'  "T  "J 

tf. 

/ 

'  * 

3 

1 

0) 

« 

i 

o 

( 

\ 

Z 

1 

1         i 

*^ 

\ 

Fig. 

''^\'- 


L^-t- 


way  motors.  The  locomotive  on  which  they  are  mounted  has  four 
driving  axles,  upon  each  of  which  is  mounted  an  armature,  direct, 
no  gears  being  used.  Figs.  16  and  17.  The  motors  are  remarkable 
for  three  .special  features:  The  method  of  mounting  the  armature, 
the  shape  of  the  pole  pieces,  and  the  path  of  the  magnetic  flux. 


16 


ELEC'TUIC    KAILWAYS 


The  nioiintinfj  of  the  arnmtiire  upon  the  driving  axle  and  tlie 
motor  fields  on  the  tnu-k  frame  makes  it  necessary  to  liave  Hat  pole 
pieces  in  order  that  the  armature  may  play  uj)  and  down  as  the 

journal  l)ox  and  axle  slide 

in  the  guides  of  the  truck 

frame.     The  shape  of  the 

pole   pieces   may  be  ol)- 

served    in    the    drawing 

Fig.    IG.     When    in    the 

central  position   there  is 

a  3 -inch  air  gap  between 

~       the    armature    and    pole 

§       pieces.     The    magnetic 

\       flux  is  continuous  through 

£       the  fields  of  all  four  of 

f       the  motors.       It  returns 

t       through    the    cast    steel 

■;"       side  frames  of  the  truck 

5?       and   two  bars  placed  in 

i       the  path. 

f  The    brush    holders 

^       are  so  mounted  that  the 
.5       brushes    ()ccu])y  a   fixed 
z       position    relative    to    tlie 
I       armature.      The   arma- 
ture is  removed  by  low- 
~.       ering  it  with  the  wheels 
'^      and   axle   upon  which  it 
is  mounted.     This  can  be 
done   without  disturbing 
the  fields  of  the  motor. 

CONTROLLERS. 

In  an  ordinary  electric 
car,  current  is  taken  from 
tlie  wire  through  the  trolley  wheel  and  ])ole,  and  is  first  led  from 
the  trollev  base  throui;h  overhead  switches  or  a  circuit  breaker,  and 
then  to  the  controller,  from  which  it  passes  through  the  motors  and 


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cc     '^^ 

o  t; 

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a 

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o    " 

o 

o 


cc 

H 

u 

u 
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01 


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ABvaan 


ELECTRIC    RAILWAYS  17 


thence  througli  the  motor  frames,  car  truck,  and  wheels  to  the  rails 
and  ground.  If  the  car  is  designed  to  be  operated  from  either  end, 
an  overhead  switch  or  circuit  breaker  is  placed  over  each  phitform 
of  the  car  so  that  current  can  instantly  be  cut  off  entirely  from  the 
controllers  by  throwing  the  switch  or  circuit  breaker  at  either  end 
of  the  car. 


Fig.  17.     Armat  nn;  Axle  ami  Wheels. 

The  lighting  circuit  is  run  from  the  trolley  base  independently 
of  the  motor  circuit,  and  has  its  own  switch  and  fuse  box.  Current 
for  the  lights  is  taken  from  the  trolley  circuit  before  it  reaches  the 
main  switches  or  circuit  l)reakers.  furrent  for  electric  heaters,  if 
such  are  used,  is  likewise  taken  from  a  separate  circuit.  On  a  oOO- 
volt  system  five  100-volt  lamps  are  usually  connected  in  series  for 
car  lighting.  As  many  multiples  of  five  can  be  employed  as  are 
necessary  to  light  the  car. 

Rheostat  Control.  The  simplest  form  of  controller  is  that 
employed  where  only  one  motor  is  u.sed  on  a  car.  A  rheostat  is 
placed  in  series  with  the  motor  when  started,  just  as  on  a  stationary 
motor;  and  the  function  of  the  controller  is  to  short-circuit  this 
resistance  gradually  until  it  is  entirely  cut  out  and  the  motor  operates 
with  the  full  voltage.  The  controller  also  has  a  leversing  switch 
by  means  of  which  the  relative  connections  of  the  armature  and  fields 
are  reversed,  which,  of  course,  changes  the  direction  of  rotation  of 
the  motor  armature.  Such  a  simple  e(juipment  as  this,  however, 
is  rarely  to  be  found  in  practice. 

Series=Parallel  Control.  Single-truck  cars  usually  have  two 
motors,  one  on  each  axle;  and  on  such  cars  a  series-parallel  controller 


18  ELECTRIC    KAIL  WAYS 


is  tlu'  kind  usuallv  cuiplinrd.  l)iati,rams  of  coiiiu'ctidiis  on  the 
various  points  of  a  series-parallel  controller  (Type  K  (1)  of  the  (ien- 
eral  Electric  Company,  are  given  in  Fig.  IS. 

^Ofnf    Res/stance       Mo/or  f  Motor  2 

Armafure    rie/cf       Armature     Fie/cf 


-=-wwvwy 


p-ijr.  18.    Diagram  of  K6(  out  rolk'iCombinatious. 

From  these  (lia}i!;rams  it  is  seen  that  the  motors  are  first  o|)era.te<l 
in  series  until  all  the  resistance  is  short-circuited  V)V  the  controller. 
^Vhen  this  has  occurred,  the  cars  are  rumiing  at  about  half  speed. 
The  next  point  on  the  v,ontroller  puts  the  two  motors  in  multiple, 


ELECTRIC    KAIL  WAYS 


19 


with  sonic  n'.si.st;mc<'  in  the  circnit,  wliicli  resistance  is  cnt  out  upon 
tl»e  f()ll<)\vin<i;  ])()ints,  until  at  full  speed  the  two  motors  are  in  nniltiple, 
without  anv  resistance  in  the  circuit. 

Four  Motori--.  \Vhere  four  motors  are  used  on  a  cai',  as  is 
frequently  the  case  witli  douhle-truck  cars,  the  motors  on  each 
truck  are  usually  controlled  just  as  in  case  of  the  two-motor  e((uip- 
i::ent  that  has  been  described;  hut  each  pair  of  motors  is  o])erated 
i:i  multiple.     That  is,  on  the  fir.st  points  of  the  controller,  the  two 


•>CVM5     ^Oc/'QM" 


-<y^RX5    xy^'^M' 


I-Mlt.  r.i.    ]Vri)t<)r  in  Scrii's. 


motors  of  a  pair  are  in  .series,  as  in  Fig.  ]\),  and  the  two  ])airs  are 
in  parallel;  and  on  the  last  points  of  the  controller,  all  the  motors 
are  in  parallel,  as  in  Fig.  20. 

The    controlle"    (Type   K)    shown 
open  in  Fig.  l21,  which  in  its  vari- 


Contrcller    Construction 


-<M5W 


-KVtm" 


ous  forms  is  the  type  most  com- 
monly used  on  street  cars  in  the 
United  States,  has  a  contact  cylin- 
der  or  drum  mounted  upon  the 
main  shaft  of  the  controller.  This 
contact  drum  carries  contact 
rings  insulated  from  the  drum, 
and  is  suitably  interconnected,  as 
indicated  In  Fig.  22,  which  .shows 
the  contact  rings  of  the  controller 
as  they  w^ould  appear  if  rolled  out  (hit.  Contact  fingers  are  placed 
along  the  left  side  of  the  controller,  as  seen  in  Fig.  21,  one  for  each 
ring  on  the  drum;  and  as  the  controller  handle  is  turned  to  revolve 
this  drum,  the  contact  fingers  make  contact  with  the  rings  on  the 
drum  and  give  the  various  connections.  Alongside  the  main  con- 
troller drum  is  a  reverse  drum  which  simply  reverses  the  armature 
connections  of  the  two  motors. 


L-KV^M 


I''i.tr. -JO.     Mi.idi-  iiiP;ir:ill. 


20 


ELECTUIC    RAILWAYS 


Controller  Wirinjj.  'I'lio  connection  1)0t\V(MMi  motors,  con- 
t]-o]lers,  and  resistances,  with  two  motors  and  a  K  (»  controller  is 
shown  in  Fig.  22.  A  carefnl  stndy  of  this  will  show  the  combinations 
to  be  the  same  as  indicated  in  the  diagram,  Fig.  IS.  'J'he  wiring 
is  rather  complicated;  and  in  practice,  to  avoid  confnsion,  the  ends 
of  each  wire  are  labeled  with  tags  showing  the  terminals  to  which 
thev  beloner. 


'-.dA. 


S5^*= 


FiK-2I.    ('imtrollcr. 


With  the  aid  of  Figs.  22,  2))  and  24,  the  wiring  of  a  type  K  0 
controller  with  two  motors  may  ])c  followed.  Figs.  2'A  and  24  are 
for  a  different  controller  bnt  can  be  used  to  assist  in  an  understanding 
of  the  complicated  diagram  22.  The  current  leaves  the  choke  or 
kicking  coil  of  the  lightning  arrester  and  passes  through  the  blow 
out  coil  of  the  controller.  It  then  goes  to  the  top  finger  T  of  the 
controller.  On  the  first  point  the  circuit  is  as  shown  in  Fig.  23. 
The  top  segment  A.  makes  contact  with   the  top   or  trolley  finger. 


•)•> 


ELECTRIC    RAILWAYS 


"*•     CfKOUNO 

Fig.  23.     Motors  in  Series. 


All  Imt  the  lower  \\\v  .sctriiic'iit.s  of  the  cvliiider  tire  electrltallv  con- 
netted  togetlu-i'  hy  mean.s  of  the  iron  cylinder  upon  which  they  are 
ir.ounted.  On  the  first  point  then  the  current  pas.ses  from  the 
cylinder  over  H,,  and  with  ,strai<;ht  series  connections  of  the  resi.st- 

ances,  it  goes  through  all 
of  the  rheostats  under 
the  car,  and  returns  to 
the  controller  over  the 
last  resistance  lead,  Ilj. 
Behind  the  motor  cut-out 
switches  at  the  base  of  the 
controller  this  lead  istap- 
])cil  into  a  wire  one  end 
of  which  leads  to  finger 
1*.)  of  the  controller,  and 
the  other  end  through 
the  cut-out  switch  and 
reverse  cylinder  to  No.  1 
armature.  The  current 
takes  the  latter  path,  pas.ses  through  the  armature  of  the  motor  and 
returns  hv  wav  of  the  reverse  cylinder,  thence  throuHi  the  fields  of 
Xo.  ]  motor  and  then 
through  the  cut-out  switch 
of  No.  1  motor  and  to  finger 
E , ,  of  the  controller.  Seg- 
ments (),  M,  Nand  !>,  shown 
in  Fig.  2.3,  and  corre.spond- 
ing  segments  of  Figs.  22 
and  24,  are  insulated  from 
the  remainder  of  the  con- 
troller cylinder.  From 
finger  E,  and  segment  () 
f Fig.  23)  the  current  pas.ses 
over  finger  1.'3  through  No. 
2  cut-out  switch  and  the 
reverse  cylinder  to  the  arm- 
ature of  No.  2  luotor.  Returning  ii  passes  through  the  reverse 
cylinder,  then  hack  through   the  fields  of  No.  2  motor   and  to  the 


Fin. -JJ 


C/'OUNO. 

Motors  ill  Purallel. 


ELECTRIC    RAILWAYS  23 


ground,  which  is  usually  through  a  connection  on  the  motor  casing. 

C)n  points  2,  3,  4  and  5,  the  successive  series  points  of  the  con- 
troller I{|,  K  ,  etc.,  make  contact  with  segn.ents  B,  C,  etc.,  Figs.  23 
and  24,  until  finally  finger  10  rests  on  segments  J,  the  resistance  is 
ail  cut  out  and  the  motors  are  connccte<l  in  series  directly  across  the 
line.  A  further  movement  of  the  controller  handle  changes  the 
motors  from  series  to  nniltiple  connection  and  inserts  in  the  circuit 
a  j)ortion  of  the  external  resistance.  There  are  four  se])arate  stages 
in  making  this  change.  First,  the  resistance  fingers  slide  oft"  their 
segments  and  the  resistance  is  inserted  in  the  line.  Second,  fingers 
E|  and  G  make  contact  with  segments  P  and  Q.  Motor  No.  1  is 
then  across  the  line  in  series  with  the  resistance;  the  circuit  being 
from  E,  to  ground  over  G.  When  the  lower  finger  E,  makes  contact 
with  P,  the  upper  one  has  not  yet  left  segment  O.  This  short-circuits 
No.  2  motor,  the  path  being  from  the  ground,  up  wire  G,  thence  by 
way  of  segments  P  and  Q  and  through  connecting  clip  V,  between 
the  two  E|  fingers  back  through  finger  1.5  to  the  motor. 

A  further  movement  of  the  controller  handle  causes  the  fingers 
to  leave  segments  M  and  ()  and  No.  2  motor  is  open-circuited  until 
finger  1.5  makes  contact  with  segment  N.  When  this  takes  place 
the  motors  are  in  multiple.  On  the  successive  points  after  this  the 
external  resistance  is  cut  out  in  the  same  manner  as  previously 
described. 

By  reference  to  Fig.  22,  it  will  be  noticed  that  the  leads  to 
the  motors  and  the  resistances  are  tapped  on  wires  of  the  cables 
connecting  the  two  controllers  on  the  ends  of  the  car.  The  two  ends 
of  these  wires,  with  the  exception  of  the  armature  wires,  lead  to 
similar  binding  posts  on  the  two  controllers.  The  armature  wires 
are  interchanged  connecting  at  one  controller  into  binding  post 
A  A^  while  the  other  end  connects  into  binding  post  A.  This  change 
of  connection  is  necessary  in  order  that  the  reverse  handles  be  for- 
ward for  forward  direction  of  movement  of  the  car. 

To  reverse  a  series  motor  it  is  simply  necessary  to  reverse  the 
direction  of  flow  of  the  current  in  either  the  armature  or  field.  For 
several  reasons,  it  is  advantageous  in  the  case  of  the  street  railway 
motor  to  reverse  the  current  in  the  armature  rather  than  in  the  field. 
Figs.  2.5  and  20  show  how  this  is  accomplished.  'Jlie  squares  shown 
in  the  figures  represent  the  lugs  on  the  reverse  cylinder  as  shown 


24 


ELECTRIC    RAILWAYS 


in  Fi<:. 


2\.  With  the  reverse  handle  in  one  po.siti«)n  (Fi^.  25),  the 
large  lugs  are  under  the  reverse  fingers,  and  current  passes  from 
finger  19  to  finger  A,,  and  from  finger  15  to  finger  A..     Fig.  2G  shows 

the  relative  position  of  reverse 
fingers  and  lugs  for  the  reverse 
position  of  the  controller  han- 
dle. In  this  case  the  current 
passes  from  finger  10  to  A  A,, 
and  from  finger  15  to  finger 
A  A_..  The  effect  is  to  change 
the  <lirection  of  flow  in  the 
armatures  while  that  in  the 
Hekls    remains    the    same    a^ 

Fig.  2.-).    Forward  Position  of  Reverse.  may  y)e  observed  bv  the  arrOWS. 

Wiring  of  Type  L  Controllers.  The  type  L  controller, 
shown  in  Fig.  27,  while  accomplishing  the  .same  results  as  the  type  K, 
is  wired  in  a  radically  different  manner.  The  circuit  is  opened  in 
changing  from  series  to  multiple  connections.  The  controller 
handle  makes  two  complete  revolutions  in  moving  froni  the  series 
to  the  multiple  position.  It  is  geared  to  the  rheo.static  cylinder 
in    such    a    manner    that    the 


A/o.a 


■« AAA 

»  Ajf 


JS 


r. 


Q 


■AA, 


A. 


B 


first  half  of  both  the  first  and 
second  revolutions  gives  this 
cylinder  one  complete  turn. 
During  the  second  half  of  the 
revolution  the  cylinder  is  re- 
turned to  its  original  position. 
The  controller  handle  is  .so 
connected  to  the  commutating 
arm  that  this  stands  in  a  cen- 
tral position  for  the  off  position 
of  the  handle.  At  the  begin- 
ning of  the  first  revolution  it  is  swung  to  the  left,  throwing  the 
motors  in  series.  At  the  beginning  of  the  second  revolution  it  is 
moved  to  the  right,  putting  the  motors  in  multiple. 

The  rheostats  instead  of  being  wired  in  series  are  connected 
in  multiple.  Current  passes  from  the  blow-out  coil  to  the  bottom 
"fingers  of  the  controller  S,   and   thence  to  the  rheostats.     On  the 


■>  IS 


B 


Vis.  Ofi.    'Reverse  Position  of  Reverse. 


ELECTRIC    KAILWAYS. 


25 


26  ELECTKIC    KAIL  WAYS 


first  ]K)int  the  current  returns  over  R,   to  the  controller  cylinder. 
It  passes  off  through  a  collar  at  the  base  of  tlie  cylinder  through  No. 

1  cut-out,  and  the  reverse,  which  is  shown  in  the  central  position,  to 
No.  1  motor.  On  returning  lo  the  controller  over  K,  it  passes  to 
t!;e  upper  section  of  the  coniniutating  arm.  In  the  diagram  this 
is  shown  in  the  central  position.  In  series  it  is  thrown  to  the  left. 
The  current  then  passes  from  the  commutating  arm  to  No.  2  cut-out, 
and  to  No.  2  motor.  jMovement  of  the  controller  handle  further 
nniltiplies  the  paths  through  the  rheostats  and  finally,  when  fingers 
S  rest  on  the  cylinder,  the  rheostats  are  short-circuited.  If  the  con- 
troller handle  is  moved  still  farther,  the  rheostat  cylinder  is  returned 
to  the  off  position  and  the  commutating  arm  is  thrown  to  the  left. 
^Yith  the  arm  in  this  position  the  current  divides,  one  portion  passing 
to  No.  1  motor  as  before  and  to  ground  by  way  of  the  upper  section 
of  the  commutating  arm ;  while  the  other  branch  goes  by  way  of  the 
lower  section  of  the  commutating  arm  to  the  cut-out  switch  for  No. 

2  motor  and  thence  to  the  motor. 

Reversing  is  accomplished  by  onc-({uartcr  revolutions  to  the 
riffht  and  left  of  the  segments  shown.  It  is  evident  that  this  will 
ccmnect  either  A,  or  A  A,,  to  the  trolley.  And  likt-wise  connect  the 
other  armature  leads. 

Reversal.  The  reversing  handle  and  the  main  controller  handle 
are  made  interlocking  so  that  the  motors  cannot  be  reversed 
without  first  throwing  the  controller  to  off  position.  This  is  to  pre- 
vent daiuage  to  the  motors  through  careless  or  inadvertent  throwing 
of  the  reverse  handle  when  the  controller  is  on  some  of  its  higher 
points.  Such  a  reversal  would  cause  an  enormous  current  to  flow 
through  the  motors,  and  would  l)e  likely  to  damage  them  and  to 
open  all  the  circuit  breakers  and  fuses  in  that  circuit.  The  reason 
for  the  enormous  flow  of  current  is,  of  course,  that  the  coimter- 
electromotive  force  of  the  motors,  when  reversed  with  the  car  going 
at  some  speed,  would  materially  add  to  the  electromotive  force  of 
the  trollev  line,  instead  of  opposing  it  as  when  the  cars  are  in  opera- 
tion. The  current  flowing  through  the  motor  circuit  would  then  be 
e([\\a\  to  {clecfromotivc  force  of  line  +  clcciromotivc  force  of  moiors)  -r- 
{resisiance  of  .noiors),  which  would  result  in  a  very  large  current. 

riagnetic  Blow=Out.  On  the  Type  K  controller  as  well  as  on 
most   other   successful   controllers,    the   flashing  or   arcing   l>et\veen 


ELECTRIC    RAILWAYS  .  27 


contact  rings  and  fingers,  which  occurs  when  the  circuit  is  broken, 
is  materially  reduced  by  a  magnet  that  produces  what  is  called  the 
magnetic  blow-out  to  extinguish  the  arc.  This  magnet  derives  its 
current  from  the  main  circuit,  and  is  so  arranged  as  to  create  a 
stnmg  magnetic  field  in  the  neighborhood  of  the  place  where  the 
arc  is  formed  Fig.  21  shows  a  Type  K  controller  open  with  the 
magnetic  blow-out  magnet  thrown  back  on  a  hinge.  The  coil 
which  produces  this  magnet  is  seen  in  the  right  side  of  the  con- 
troller. The  main  contact  drum  is  in  the  middle,  and  the  revers- 
intr  drum  at  the  right  hand.  There  are  in  use  a  number  of  other 
controllers  built  upon  these  same  general  principles  but  differing  in 
mechanical  arrangement. 

Controller  Notches.  All  controllers  are  provided  with  some 
device  which  prevents  the  motorman  from  stopping  the  controller 
handle  between  the  various  points  or  notches,  as  the  stopping  be- 
tween points  might  result  in  drawing  an  arc  or  an  imperfect  con- 
tact. The  most  common  arrangement  to  prevent  this  is  a  notched 
wheel  on  the  controller  shaft,  against  which  bears  a  small  wheel  of 
just  the  right  size  to  enter  the  notches.  The  small  wheel  is  held 
against  the  notched  wheel  by  a  strong  spring.  As  the  tendency 
of  the  small  wheel  is  to  seek  the  bottom  of  the  notches,  it  is  diffi- 
cult to  stop  the  controller  handle  anywhere  between  notches,  and 
the  motorman  is  thus  given  a  guide  which  tells  him  without  any 
effort  on  his  part  just  where  the  notches  are. 

To  prevent  advancing  the  controller  handle  too  rapidly  and 
avoid  the  jerking  of  passengers,  excessive  currents  and  slipping  of 
wheels  during  acceleration,  several  devices  have  l)een  planned.  On 
the  multiple  unit  control  systems,  a  limit  switch  is  usually  provided 
which  prevents  the  controller  advancing  when  the  current  exceeds 
a  predetermined  amount.  A  device  to  accomplish  the  same  results 
on  the  K  type  of  controllers  is  teriiied  the  Automotoneer.  A  cam 
connected  with  a  dash  pot  prevents  movement  of  the  controller 
handle  to  the  successive  notches  faster  than  a  previously  prescribed 
rate. 

A  switcii  is  usually  pnn'ided  in  a  controller,  for  cutting  out 
of  service  one  motor  or  a  pair  of  motors  if  defective,  and  allowing 
the  car  to  proceed  with  the  good  motor  or  motors. 


28 


ELECTRIC    llAILWAYS. 


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^IVERSITV  oflUINQl 


ELECTRIC    RAILWAYS  29 


MULTIPLE=UN1T   CONTROL. 

A  system  called  'Snultij)le-iinit  control"  or  "train  control" 
has  come  into  nse  where  it  is  desired  to  operate  motors  imder  a  number 
of  different  cars  in  a  train;  all  the  motors  being  controlled  from  the 
head  of  the  train  or  from  any  other  point  on  the  train  where  the 
inotorman  may  be  stationed. 

There  are  several  types  of  multiple-unit  control,  in  all  of  tlieni 
there  is  on  each  car  a  controller  of  some  kind  which  controls  the 
current  flowing  to  the  motors  on  that  car.  This  controller  is  operated 
from  a  distance  by  means  of  electro-magnetic  or  electro-pneiunatic 
devices  controlled  by  circuits  called  jjilot  circuits,  which  circuits  are 
connected  to  the  motorman's  controller.  x\ll  the  pilot  circuits  of  a 
train  are  connected  together  by  means  of  train  plugs  which  make 
the  connections  between  the  cars.  The  pilot  circuits  of  each  car 
are  connected  to  a  motorman's  controller  on  that  car  and  this  makes 
it  possil)le  to  operate  the  train  from  any  controller. 

Sprague  Multiple=LJnit  System.  Jn  the  earliest  form  of 
multiple-unit  control — which  was  that  devised  by  F.  J.  Sprague — 
the  motors  on  each  car  were  controlled  by  an  ordinary  Type  K  con- 
troller, which  had  geared  to  its  shaft  a  small  ])ilot  motor.  The 
pilot  motor  was  controlled  by  the  pilot  circuits  connected  with  the 
motorman's  controller. 

In  the  more  recent  forms  of  multiple-imit  control,  the  use  of 
main  controllers  having  contact  cylinders  has  been  practically  aban- 
doned. Tlie  contacts  are  made  instead  by  a  number  of  electro-mag- 
netic or  electro-pneumatic  contact  devices  sometimes  called  coniaciors. 

General  Electric  Train  Control.  In  the  General  Electric 
train-control  system  each  contact  for  the  motor  circuits  is  made 
by  a  solenoid  magnet  which  draws  together  two  heavy  copper  con- 
tact fingers  to  establish  the  circuit.  A  magnetic  blow-out  coil  in 
series  with  the  contact  is  also  provided.  The  contactors  make 
contact  only  when  energized  by  a  small  amoun.t  of  cm-rent  from 
the  master  or  motorman's  controller.  In  Fig.  2S«  is  a  diagram  of 
the  car  wiring  for  a  motor  car  equipped  with  this  system.  The 
motorman's  controller  is  a  drum  controller,  but  is  comparatively 
small  since  it  has  to  handle  only  the  small  amount  of  curreirt  necessary 
to  opc'-ate  the   solenoid   magnets  of  the  contactors.     It  is  evident 


30  ELECTKIC    KAILWAYS 


that  l)_v  coiiiuTtiiii;'  tc)*;vther  the  pilot  ciix'iit.s,  %vhich  are  eoniiected 
to  the  niotornian's  controller,  so  that  the  pilot  circuits  will  be  continu- 
ous for  the  entire  length  of  the  train,  any  number  of  cars  ecjuipped 
with  the  train-control  system  can  be  ojjcrated;  aiwi  similar  contacts 
will  be  made  by  tiic  contactors  under  all  the  cars  simultaneously, 
by  virtue  of  the  circuits  established  by  the  master  controller  at  any 
platform. 

Besides  controlling  tlic  contactors,  the  master  or  niotornian's 
controller  must  control  an  electro-magnetic  reversing  switch,  or 
reverscr,  to  change  the  direction  of  car  travel. 

The  handle  of  the  niotornian's  controller  is  provided  with  a 
push  button,  which  must  be  depressed  while  the  current  is  turned 
on.  Should  the  motorman  release  this  push,  the  circuit  through 
the  controller  will  be  opened  and  all  the  contactors  will  fall  open. 
This  handle  is  called  the  dead  nian's  handle  because  it  is  put  the'^e 
to  j)rovi(le  for  cutting  off  the  current  should  the  motorman  fall  dead 
or  in  a  faint  at  his  post. 

The  flow  of  the  ciu'rent  in  the  control  circuits,  which  operates 
the  reverser  and  picks  up  the  contactors  on  the  several  points  may 
be  followed  in  the  diagram  Fig.  28rt.  With  the  reverse  handle  in 
the  forward  })osition  and  the  controller  on  the  first  point,  current 
])asses  fnmi  the  main  circuit  through  a  single-pole  fused  switch 
called  the  control  switch  and  through  the  auxiliarv  blow-out  coil 
to  a  finger  bearing  on  the  upper  section  of  the  master  controller 
cylinder  by  which  connection  is  established  to  the  atljacent  finger 
and  thence  to  the  reverse  cvlinder.  It  leaves  this  over  wire  Xo.  S, 
passing  by  way  of  the  connection  board  and  control  cut-out  switch 
to  the  forward  operating  coil  of  the  reverser,  thence  through  the 
forward  blow-out  coil  and  over  wire  81,  through  the  switch  under- 
neath contactor  No.  2  and  to  ground  G,  by  way  of  wire  B  2  after 
passing  through  the  fuse  shown.  The  current  through  the  operating 
coil  of  the  reverser,  having  thrown  tliis,  the  })ath  is  changed  some- 
what. The  current  then  instead  of  passing  from  the  rever.ser  over 
wire  81,  is  conducted  through  wire  15,  through  the  operating  coils 
of  contactors  No.  1,  2,  8,  and  11  in  series,  through  the  switch  under 
contactor  No.  12,  and  to  ground  through  finger  1  of  the  controller. 
Contactors  1  and  2  are  in  multiple  and  when  raised  connect  the 
trollev  with   the  contactors  controllinji;  the   resistance  leads.     Con- 


ELECTRIC    RAILWAYS  31 


tactor  3  connects  11  to  the  line  while  contactor  11  places  the  two 
motors  in  series.  The  motors  then  operate  with  all  of  the  resistance 
in  circuit.  When  contactor  2  raises,  it  opens  the  switch  immediately 
below  it,  making  it  impossible  for  the  reverse  to  operate  while  current 
is  flowing  through  the  motors.  On  the  second  notch  of  the  controller 
an  additional  })atli  is  opened  by  way  of  finger  3  of  the  controller. 
This  path  leads  from  finger  3  through  four  of  the  control  circuit 
rheostat  coils,  through  contactor  No.  5  and  to  ground  over  32.  ( )n 
the  3rd,  4th  and  5th  points  contactors  G,  7  and  9  respectively  are 
raised.  The  motors  are  then  in  full  series.  Between  the  5th  and 
6th  points  all  the  control  circuits  are  broken  preparatory  to  starting 
the  multiple  connections  of  motors.  On  the  6th  or  the  first  multiple 
point  the  ground  through  finger  1  of  the  master  controller  is'opened 
while  a  ground  through  finger  3  is  established.  The  current  from 
the  reverser  then,  after  raising  contactors  1  and  2  as  before,  instead 
of  passing  through  contactors  3  and  11,  passes  through  the  coils 
of  4,  12  and  13,  through  the  switch  under  contactor  11  and  to  ground 
over  finger  2.  Contactor  12  connects  motor  No.  2  to  Rj,  while 
contactor  13  grounds  No.  1  motor.  The  motors  now  operate  in 
parallel  and  on  successive  notches  of  the  controller,  contactors  6,  7, 
8,  and  9  are  raised,  cutting  out  all  of  the  resistance.  The  switches 
underneath  contactors  11  and  12  make  it  nn possible  for  11  to  raise 
with  12  and  13  or  vice  versa.  The  reason  for  this  arrangement  is 
very  evident,  as  a  direct  ground  for  R^  would  result. 

The  Westinghouse  Electro=Pneumatic  System  of  ControL 
In  this  system  of  multiple  unit  or  train  control,  the  current  to  the 
motors  is  supplied  through  a  set  of  unit  switches  or  circuit  breakers 
which  are  sometimes  placed  in  a  circular  case  or  turret  underneath 
the  car  and  in  other  cases  are  ranged  in  a  row  under  the  car.  The 
opening  and  closing  of  these  unit  switches  is  done  with  compressed 
air  actmg  on  a  piston  in  an  air  cylinder.  When  the  circuit  is  to  be 
closed,  compressed  air  is  admitted  behind  the  piston  and  forces  it 
down  against  the  tension  of  a  seventy-poimd  spring,  and  the  contacts 
are  brought  together.  When  the  switch  is  to  be  opened,  the  air  is 
let  out  of  the  cylinder  and  the  spring  forces  the  piston  back.  The 
air  supply  is  obtained  from  the  storage  tanks  of  the  air  brake  system. 
The  valve  controlling  the  air  supply  to  the  cylinder  of  each  unit 
"twitch  is  operated  by  electromagnets  which  derive  current  from  a 


32 


ELECTRIC    RAILWAYS 


seven  cell,   fourteeii-volt,   storai^e  battery.     The  small   master  coii- 


j^o  ;/>j  ■-♦«•  ^ui  7 


y  f/V  x^  uoijou^f 


OOOOOOOOO 


'->(^y^^ 


1(0°^ 


f  9 


'■''-■/  gLZ 


/./oj  i.Ass^ffo 


troller  operated  by  the  motorman,  makes  and  breaks  the  battery 
connections  to  the  majjnets  controlling  the  air  valves. 

An  advantage  of  this  over  other  mnltiple-unit  systems  is  that  by 


ELECTRIC    RAILWAYS  33 


the  use  of  battery  ciinent  the  control  system  is  not  (Hsturl)ecl  by 
interruptions  of  the  main  supply  of  current.  The  chief  advantage 
of  this  is  that  it  makes  it  possible  to  reverse  the  motors  and  operate 
them  as  brakes  in  emergencies  at  all  times. 

The  battery  is  charged  from  the  nuiin  line  through  lamps  as 
resistance,  or  may  be  charged  by  being  connected  in  series  with  the 
air  compressor  motor. 

In  the  accompanying  diagram,  Fig.  2.S  /;,  there  are  two  batteries 
shown  which  are  charged  in  series  with  the  compressor  motor.  Bv 
means  of  two  double-pole,  double-throw  switches,  first  one  and  then 
the  other  battery  is  connected  for  charging  and  for  service.  The 
battery  is  charged,  in  shunt  with  a  resistance  and  a  relay  is  connected 
in  the  circuit  as  shown,  so  as  to  open  the  battery  circuit  whenever 
the  current  through  the  motor  stops,  and  thus  prevent  the  battery 
discharging  through  the  resistance. 

The  master  controller  has  a  double  set  of  segments  in  order  to 
decrease  the  length  of  the  shaft.  The  handle,  therefore,  is  moved 
only  one-sixth  of  a  revolution  from  oft"  to  full  speed.  The  various 
circuits  can  be  traced  by  the  letters  and  mnnbers  each  wire  bears, 
so  that  the  circuits  will  not  be  gone  over  in  detail.  The  first  position 
of  the  master  controller  throws  the  reverser  switch  in  the  proper 
direction  and  also  closes  the  main  circuit  breaker.  On  the  second 
point  the  motors  are  connected  in  series  with  all  resistance  in  circuit, 
and  these  resistances  are  automatically  cut  out  one  by  one.  On  the 
next  point  of  the  controller  the  motors  are  in  multiple  and  the  resist- 
ances are  automatically  cut  out  in  a  similar  manner.  The  automatic 
cutting  out  of  resistances  is  accomplished  by  a  limit  switch  in  con- 
junction with  operating  and  holding  coils  on  the  electro-pneumatic 
valves.  This  limit  switch  is  a  kind  of  a  relay  which  has  the  current 
from  one  of  the  motors  flowing  through  its  coil  and  which  acts  to 
open  a  certain  battery  circuit  which  operates  the  electro-pneumatic 
valves  whenever  the  current  in  the  motor  circuit  in  question  exceeds 
the  amount  for  which  the  limit  switch  is  set.  The  automatic  accelera- 
tion or  cutting  out  of  resistance  is  accomplished  as  follows: 

Each  electro-pneiunatic  valve  has  two  magnet  coils,  one  of  which 
is  an  operating  coil  and  the  other  a  holding  coil  for  holding  the  valve 
open  after  it  is  operated.  When  first  the  cm-rent  flows  through  a 
circuit  to  one  o^  the  electro-pneumatic  valves,  it  flows  through  the 


34 


ELECTKIC    RAILWAYS 


operatiiit;  coil  and  operates  the  val\»'  to  close  the  corrc .;j)on(li)i<:; 
switch  or  switches  of  the  main  circuit  by  turninif  the  air  into  the  cylin- 
ders. As  soon  as  the  main  switch  is  closed,  it  cuts  into  circuit  the 
holding  cril  of  its  corres])ondino;  electr()-j)neuniatic  valve  and  this 
coil  will,  with  the  hattery  current,  hold  the  switch  closed  even  thouj^h 
the  circuit  to  the  ()])eratin<i;  coil  may  he  opcnecl  momentarily  by  the 
limit  switch  as  each  step  of  resistance  is  cut  out.     'i'his  ])revents  the 

Trolley 


Fuse 
Sv\/itch  /58. 


Pig.  29.     Diagram  of  Kli'ctric  Hi-atcrs. 


switches  from  openin<i;  when  they  are  once  closed  and  allows  the 
operating  coils  to  open  an  air  valve  each  time  the  current  through  the 
lin)it  switch  coil  falls  helow  the  amount  for  whic-h  it  is  set.  The 
contacts  which  close  the  holding  coil  circuit  on  each  valve  whenever 
a  main  switch  is  closed,  are  called  interlocks  and  are  indicated  on  the 


diagram. 


The  main  line  circuit  breaker,  which  is  electro-pneumatically 
operated,  will  jpen  automatically  on  overload  and  can  be  re.set  by 
the  motorman  on  all  the  cars  of  a  train  by  closing  a  switch  located 
beside  each  controller. 

CAR    HEATERS. 

Electric  Heaters  for  warming  cars  in  winter,  consist  of  iron 
wire  coils  which  are  warmed  by  the  passage  of  electric  current  through 
them.  The  heat  so  evolved  varies  as  the  resistance  multiplied  by 
the  sfjuare  of  the  current.  The  iron  wire  coils  of  the  heater  are 
mounted  on  non-combustible  insulating  supports,  and  are  arranged 


ELECTRIC    RAILWAYS 


so  that  there  is  u  free  eireiilatioii  of  air  tlirougii  tlieifi.  The  coils 
are  siirroiindetl  with  a  perforated  metal  case,  the  object  of  which 
is  to  prevent  injury  to  the  coils  and  to  prevent  persons  or  clothing- 
coming  in  contact  with  the  hot,  live  wires  of  the  coils.  Heaters  are 
sometimes  arranged  so  that  they  can  be  connected  in  series  or  parallel 
to  give  diiferent  degrees  of  heat. 

The  diagram,  Fig.  20,  shows  the  most  common  arrangement  of 
electric  heaters  recently.  The  tap  from  the  trolley  should  be  taken 
off  on  the  trolley  side  of  the  circuit  breaker.  After  passing  through 
a  fuse  the  circuit  goes  to  the  switch.  P^ach  of  the  heaters  contains 
two  coils,  one  of  higher  resistance  than  the  other.  Two  independent 
circuits  are  run  from  the  switch,  through  the  heaters  and  to  the 
ground.  One  circuit  passes  through  the  high  resistance  coils  of  the 
several  heaters  while  the  other  goes  througl  the  low  resistance  coils. 
The  switch  has  three  points.  On  the  first  point  a  circuit  is  made 
through  the  high  resistance  coils.  The  second  point  connects  the 
low  resistance  coils  while  the  third  point  puts  both  circuits  in  service. 
AVith  this  arrangement  three  gradations  of  heat  may  be  obtained. 

To  avoid  complicated  waring  sometimes  but  one  circuit  is  em- 
ployed. In  such  a  case  the  heat  must  eithci"  be  all  on  or  off,  no 
gradations  being  possible. 

The  chief  difficultv  encountered  with  electric  heaters  is  the 
breaking  of  the  wires  because  of  the  scale  of  oxide  that  forms  gradually 
when  they  are  rim  at  a  high  temperature  or  because  of  w^ater  striking 
them  from  passengers'  clothing  on  wet  days,  wdiich  causes  the  wires 
to  snap. 

The  Consolidated  Car  Heating  Company  gives  the  following 
data  on  the  current  required  to  heat  cars: 


Length  of  Car 
Hody. 

Amperes. 

Switch  Positions. 
1             2             3 

Avorace  ronditions 

•  14  to  20  f(«pt 
<;  20  to  28     " 
1  28  to  34    " 

(   18  to  24  feet 
1  28  to  34    " 

3.4  7 
3           6            9 

'ipvorpst  conditions 

4  7  11 
4           7          11 

6          8          14 

8fi 


ELECTRIC    RAILWAYS 


In  liis  Electrical  Engineers'  Hand  Ho  )k,  Mr.  Fester  gives  re.sults 
of  te.sts  niailo  on  Brooklvn  cars  as  follows: 


Oars. 

Temperature  F. 

Consumption. 

Doors. 

Windows. 

12 
12 
12 
12 
16 
16 

Contents  cu.  ft. 

Outside. 

Averase 
ill  far. 

55 
30 
49 
52 
4/5 
54 

Watts. 

Amp*  rt's 
at  5U0  volts. 

2 

2 
2 

4 
4 

850i 
850i 

sosi 
ni3i 

1012' 
1012 

'28 

7 
28 
35 

7 
28 

2295 

2325 
21  SO 
2715 
3038 
3160 

4.6 

4.6 

4.3 

4.5 

6. 

0.3 

^^  hen  not  watched  carefully  considerable  current  mav  be  wasted 
by  allowing  the  heaters  to  remain  turned  on  when  not  needed.     Many 


V\ix.  :ii).    Klfftric  Ilfutcr. 


companies  hang  out  .signs  where  motormen  may  ob.serve  them,  indi- 
cating when  the  heaters  .shall  be  turned  on  and  to  what  point. 

The  be.st  practice  in  electric  heating  is  to  have  plenty  of  heaters 
and  run  the  wire  at  a  low  temperature,  rather  than  attempt  to  heat 
with  a  few  at  high  temperature.  The  greater  the  number  of  heaters 
the  larger  the  radiating  surface  around  which  the  air  can  circulate 
and  a  given  amcnnit  of  car  heating  can  be  accompli.shed  with  less 
current  than  with  a  few  high  temperature  heaters.  The  depreciation 
of  the  lieater  wires  is  less  the  lower  the  tein])erature  at  which  they 
are  oj^erated.     An  electric  heater  is  shown  in  Fig.  30. 

Hot= Water  Heaters  are  frecpiently  used  on  large  electric  cars. 
Hot-water  pipes  are  j)laced  along  the  sides  of  the  car,  and  connected 
with  a  stove  containing  hot-water  coils  at  one  end  of  the  car.  The 
water,  as  it  is  heated  in  the  .stove  or  heater,  expands,  and  consequently 
becomes  lighter  per  cubic  inch  or  other  un'it  of  volume;  it  therefore 
tends  to  rise  when  balanced  against  the  colder  water  in  the  car  pipes. 


ELECTJUC    KAILWAYS 


3'; 


H.)t  water  leaves  the  top  of  the  lieater,  flows  up  to  an  expansion  tank 
and  tlien  down  through  tlie  car  pipin<j;,  and  hack  to  tlie  bottom  of  the 
heater.  Tlie  car  ])ipiu(!;  slopes  continuously  down  from  the  top 
connection  to  the  bottom  connection  of  the  heater.  At  the  top, 
an  openino;  to  the  atmosphere  is  jH'ovided  through  a  small  water 
tank,  called  an  e.vpon.sion  lank.  This  prevents  water  pressure 
bursting  the  pi])es  as  they  become  heated,  and  alknvs  any  steam 
that   may   have    formed    to    escape.     The   most   modern   hot-watei' 


FitC.:^l.     Pipes  for  Hot- W;itt-rHt':iUng. 

heaters  for  cars  are  com})letely  closed  except  as  to  the  ash  pit  at 
the  bottom  and  a  small  feed  door  in  the  top.  The  latter  is  locked 
so  that  the  fire  cannot  come  out  even  if  the  car  is  tipped  over  in  a 
wreck.     Fig.  31  shows  the  pipes  of  a  hot-water  heating  installation. 

CAR  WIRING. 

The  wires  from,  motors  to  controllers,  when  placed  in  exposed 
position  under  the  car,  are  bunched  in  cables  or  covered  with  hose. 
In  s(mie  cases  special  runways  are  provided  in  the  bottom  of  the 
car  to  accommodate  the  car  wiring.  All  the  wiring  in  a  car  should 
be  heavily  insulated  with  moisture-proof  rubber-covered  wire,  and 
further  protected  from  mechanical  abrasion  by  a  tough  outer  covering. 

Stranded  rubber  insulated  wire  is  used  almost  exclusively  for 
wiring  all  parts  of  the  car.  A  general  idea  of  the  path  of  the  motor 
circuit  wiring  may  be  obtained  by  reference  to  Fig.  22.     The  main 


88  i:ij:./i  liic   uah.ways 


load  after  leaving  the  trolley  stand  is  cleated  to  the  troUev  l)oard  on 
top  of  the  car.  At  the  end  of  the  ear  it  ])asses  through  the  roof  and 
to  the  circuit  l)reaker.  ( )u  leavin<;  the  breaker  it  is  led  down  a  post, 
through  the  floor  and  t<»  the  clioke  coil  and  lightning  arrester  under- 
neath the  ear.     It  then  passes  to  the  trolley  tenninal  of  the  controller. 

The  tap  for  the  light  wiring  (although  shown  otherwise  in  the 
drawing)  is  usually  taken  ofl^  the  main  circuit  before  the  circuit 
breaker  is  reached.  This  arrangement  allows  the  lamps  to  be 
burned  when  the  eircuit  breaker  is  open.  After  j)assing  through 
fuses  and  switches  in  the  motorman's  cab  the  circuit  for  the  lights 
is  led  through  the  car  in  moulding  concealing  it. 

The  wires  running  between  the  motors,  controllers  and  resistance 
frames  underneath  the  car,  as  has  been  stated,  are  often  carried 
in  canvas  hose.  I'sually  two  cables  are  made  up,  for  shoidd  all  the 
wires  necessary  be  ])laced  in  one  cjible  this  would  become  too  bulky 
to  be  })roj)erly  cleated  up.  'J^)  make  the  canvas  hose  waterproof 
and  to  prolong  its  life  it  is  usually  given  several  coats  of  as])haltura 
jiaint. 

The  wiring  of  the  new  cars  of  the  New  York  subwav  is  an 
example  of  the  most  advanced  practice.  All  the  wires  under  the 
cars  are  carried  in  "lorlcated"  conduit,  which  consists  of  a  wrought- 
iron  tube  heavily  enameled  both  inside  and  out.  The  motor  leads 
and  the  other  larger  wires  are  carried  in  separate  conduits.  The 
conduits  are  usually  hung  to  the  steel  beams  of  the  floor  framing 
by  strap  l)olts.  This  method  of  wiring  gives  a  reasonable  assurance 
that  it  will  not  become  defective.  IMoreover,  it  lessens  fire  risk. 
The  conrluits  are  all  groimded  and  shoukl  one  of  the  wires  come  in 
contact  with  the  conduit  carrying  it,  the  dead  gromid  resulting  would 
cause  the  fuse  to  blow  instantly,  and  all  danger  would  cease. 

RESISTANCES. 

"^riie  type  of  resistance  now  most  common  for  heavy  motor 
cMjuipment  is  in  the  form  of  cast-iron  grids,  which  are  assembled 
together  and  connected  in  series.  These  grids  are  sufficiently  stiff 
to  render  lumecessary  any  solid  insidation  between  them,  and  hence 
they  can  radiate  heat  to  the  best  advantage.  The  only  difficuiiy 
experienced  with  them  is  from  the  warping  or  cracking.  Ilesistances 
for  lighter  equijiment  are  composed   of  sheet-steel   ribbons  wound 


ELECTRIC    RAILWAYS 


89 


in  coik.  Each  turn  of  a  coil  is  insulated  from  the  next  hy  asbestos. 
( )ther  forms  of  sheet-steel  resistance  with  asbestos  insulation  between 
the  turns,  have  also  been  used.  In  Fig.  32  is  shown  a  Westino;house 
<;rid  type  diverter  for  street  railway  ecjuipment. 

ELECTRIC  CAR  ACCESSORIES. 

Canopy  Switch.  An  overhead  switch,  sometimes  called  a 
"canopy  switch,"  is  commonly  placed  over  each  street-car  platform 
where  a  controller  is  located,  usually  in  the  deck  or  canopy  above 
the  motorman's  head.  This  is  simjjly  a  single-point  switch  that 
may  be  used  by  the  motorman  to  cut  the  trolley  current  off  from  the 


(((«(*«' "(«((((( 


C(U((((((({((((((U, 


(li^cffrrrfffffj^ 


Fig.  32.    Grid  Type  of  Resistance. 


controller  wiring  so  that  the  controllers  will  be  ab.solutely  dead. 
When  two  such  switches  are  used,  one  on  each  end  of  the  car,  they 
are  connected  in  series. 

Car  Circuit  Breaker.  Fre(iuently  on  large  e(|uii)ments  an 
automatic  circuit  breaker  is  provided  in.stead  of  this  overhead  switch. 
This  circuit  breaker  can  be  tripped  by  hand  to  open  the  circuit  when- 
ever desired;  and  is  also  equipped  with  a  solenoid  magnet,  which  can 
be  adjusted  so  that  it  will  trip  or  open  the  circuit  breaker  at  approxi- 
mately whatever  current  it  is  set  for.  This  circuit  breaker  protects 
the  motor  and  car  wiring  from  excessive  current,  such  as  would 
occur  in  case  of  a  short  circuit  in  motors  or  car  wiring,  or  in  case  the 


40 


ELECTRIC    RAILWAYS 


iiiotoniiaii  turned  on  current  so  raj)i(lly  'ds  to  endanger  tlie  windint^s 

of  the  motors.     Circuit  breakers   however,  are  most  comnionly  used 

on  cars  havin*;  controllers  located  at  only  one  end  in  a  motorman's  cab. 

Wiring   of   Circuit    Breakers   and   Canopy   Switches.     Figs. 


P 


^ 


[fW^ 


FiK.  .^:^. 


33,  34,  and  35  show  the  methods  of  wiring  circuit  breakers  and  canopy 
switches  for  double-end  cars. 

In  the  parallel  connection  as  shown  in  Fig.  33,  the  trolley  leads 
after  passing  through  the  choke  coils  go  directly  to  the  blow-out 
coil  of  the  controllers.  Aside  from  the  fact  that  two  lightning  arresters 
and  choke  coils  are  required,  this  method  is  preferable  for  automatic 
cir'uit  breakers. 


\^ 


Fiv:.  ■■'>[. 

Fig.  34  shows  the  hand-operated  circuit  breakers  connected 
in  series.  'J'his  method  is  used  where  non-automatic  breakers  are 
employed,  but  for  automatic  breakers  it  has  the  objection  that  an 
overload  would  throw  the  breaker  set  at  the  lowest  point.  This 
might  be  the  breaker  on  the  opposite  end  to  that  occupied  by  the 
motorman  and  in  such  an  event  would  necessitate  a  trip  to  the  other 
end  to  set  the  breaker. 


ELECTKIC    KAILWAYS 


41 


Fig.  36  shows  a  iiietluxl  of  parallel  connection  re(juiring  but  one 
lightning  arrester.  This  method  has  the  objection  that  the  niotornian 
on  the  front  end  would  have  no  assurance  that  by  throwing  the 
breaker  over  him  the  power  would  be  cut  off.  The  rear  breaker 
might  have  l)ccn  carelessly  left  set. 


V" 


^ 


I 


^ 


] 


Fig.  85. 

Fuses.  A  fuse  is  placed  in  series  with  the  motor  circuit  before 
it  enters  the  controller  wiring,  but  where  circuit  breakers  are  used 
instead  of  canopy  switches,  the  fuse  box  may  sometimes  be  dispensed 
with.  The  fuse  box  on  street  cars  is  usually  located  underneath  one 
side  of  the  car  body  where  it  is  accessible  for  replacing  fuses,  but 
where  a  motorman's  cab  is  used,  the  fuse  may  be 
placed  in  the  cab.  The  fuse  may  be  of  any  of 
the  types  in  c(mimon  use,  either  open  or  enclosed. 
In  the  Westinghouse  fuse  box  it  is  necessary  only 
to  open  tlie  box  and  drop  in  a  piece  of  straight 
copper  wure  of  the  right  length  and  size.  The 
closing  of  the  box  clamps  this  wire  to  the  termi- 
nals and  establishes  a  circuit  through  the  cop- 
per wire  as  a  fuse.  Of  course  this  copper  wire 
is  of  small  enough  size  to  be  fused  by  a  danger- 
ously heavy  current. 

Lightning  Arresters.  A  lightning  arrester 
is  used  on  all  cars  taking  current  from  overhead 
lines.     The  lightning  arrester  is  connected  to  the 


Fig.  ;;g. 


main  circuit   as  it  conies  from    the   trolley  base, 
before  it  reaches  any  of  the  other  electrical  de- 
vices on  the  car,  so  that  it  may  afford  them  ])rotection.     A  conunon 
type  of  lightning  arrester  is  shown  in  Fig.  3().     One  lernunal  of  the 


12 


ELECTRIC    RAILWAYS 


lij;litiiiiig  arrester  is  connected  to  the  motor  frame  so  as  to  .ground 
it,  and  the  other  is  connected  with  the  trolley.  In  most  forms  of 
lightning  arrester,  a  small  air  gap  is  provided,  not  such  as  to  |x?r- 
mit  the  500-volt  current  to  jump  across,  but  across  which  the  light- 
ning will  jinnj)  on  account  of  its  high  potential.  To  prevent  an 
arc  being  established  across  the  air  gap  by  the  power  house  cun-ejit 
after  the  lightning  discharge  has  taken  place  and  started  the  arc, 
some  means  of  extinguishing  the  arc  is  provided.  In  the  General 
Electric  Company's  lightning  arrester,  the  arc  is  extinguished  by 
a  magnetic  blow-out,  which  is  energized  by  the  current  that  flows 

Trolley 


\Fuse 

\2  Point  Switch 


Sign  Light. 


o- 


Platrorrm 
Light 


o 


o 


o 


o 


o- 


■o 


Sign  Light 


Plat  forn^ 
Light. 


^9 


I       7 


4  Point  Double 


1 


'/ hro^t/  S^/^itch 


C^Heaa  Light 


Head  Light 


\ 


Fifj  ST.     Di:i<rr;iiii  iif  I, iirlit  Circuit, 


through  the  lightning  arrester.  The  instant  the  di.scharge  takes 
place  the  current  flows  across  the  air  gap.  The  magnetic  blow-out 
extinguishes  the  arc,  and  this  opens  the  circuit,  leaving  the  arrester 
ready  for  another  discharge.  In  the  Garton-Daniels  lightning 
arrester  a  plunger  contact  operated  by  a  solenoid  opens  the  cir- 
cuit as  soon  as  current  begins  to  flow  through  the  arrester.  This 
plunger  operates  in  a  magnetic  field,  which  extinguishes  the  arc. 
A  choke  coil,  consisting  of  a  few  turns  of  wire  around  a  wooden 
drum,  is  placed  in  the  circuit  leading  to  the  motors  at  a  jjoint  just 
after  it  has  passetl  the  lightning  arrester  tap.  This  choke  coii  is 
for  the  purpo.se  of  placing  self-induction  in  the  circuit,  so  that  the 
lightning  will  tend  to  branch  off  through  the  lightning  arrester  and 
to  ground,  rather  than  to  .seek  a  path  through  tlie  motor  in.sulation 
to  ground. 


ELECTRIC    RAILWAYS  43 


Often,  liowever,  the  choke  coil  is  omitted,  the  coils  in  the  circuii 
breaker  and  the  blow-out  coil  in  the  controller  being  depended  upon 
to  prevent  the  lightning  charge  from  passing. 

Lamp  Circuits.  The  lamp  circuit  of  a  car  is  protected  by  its 
separate  fuse  box,  and  usually  each  lamp  circuit  has  a  switch.  As 
explained  before,  five  100-volt  or  110-volt  lamps  are  placed  in  series 
l)etween  the  trolley  wire  side  of  the  circuit  and  ground.  If  one  lamp 
in  the  series  burns  out,  of  course,  all  five  are  extinguished  until  the 
defective  lamp  is  replaced  with  a  new  one.  Enclosed  arc  lamps 
are  sometimes  used  for  car  lighting. 

Cars  to  be  operated  from  either  end  are  often  wired  so  that  by 
turning  a  switch  the  platform  light  on  the  front  end,  a  light  for  the 
sign  and  another  for  the  headlight  on  the  rear  end  will  Ije  extinguished 
and  corresponding  lights  on  the  rear  and  front  ends  lighted.  This 
is  accomplished  l)y  the  method  of  wiring  shown  in  Fig.  37.  The 
interior  of  the  car  is  lighted  by  six  lights.  Headlights  of  32  candle 
power  are  used.  This  method  requires  the  use  of  two  switches. 
In  all  light  wiring  schemes  a  switch  should  be  placed  on  the  trolley 
side  of  the  lights.  This  permits  the  cin-rent  to  be  cut  off  in  the  event 
of  a  ground  occurring  in  the  system. 

On  interurban  cars  arc  headlights  are  almost  in\ariably  used 
The  circuit  for  the  headlight  after  passing  through  a  switch  in  the 
motorman's  cab  goes  through  a  resistance  frame  usually  imderneath 
the  car  and  terminates  in  a  socket  near  the  car  bumper.  The  brackets 
on  which  the  lamp  is  hung  are  grounded  so  that  whenever  the  plug 
from  the  lamp  is  inserted  in  the  socket  and  the  switch  in  tlie  cab  is 
turned  onj  the  circuit  is  made. 

Usually  there  is  a  pressure  of  about  GO  to  70  volts  at  the  terminals 
of  the  lamp.  The  remainder  of  the  voltage  drop,  from  500  or  GOO 
volts  (or  whatever  the  line  may  be),  is  in  the  resistance  imder  the  car. 
The  current  through  the  lamp  is  usually  about  four  amperes.  With 
60  volts  at  the  arc  and  500  volts  on  the  line,  this  gives  a  consumption 
in  the  lamp  of  240  watts  and  a  loss  in  the  resistance  imder  the  car  of 
2,000  watts,  or  about  90  per  cent.  The  use  of  the  headlight  resistance 
to  cut  the  voltage  down  is  therefore  a  very  inefficient  method.  Some 
schemes  of  wiring  use  the  incandescent  lamps  used  in  lighting  the  car 
as  resistance  for  the  headlight.  Another  wav  is  to  liii'ht  the  interior 
of  the  car  with  arc  lamps  placed  in  series  with  the  arc  headlight. 


44 


ELECTIUC    I{ATL\VAYS 


Trolley  Base.  The  trolley  base  upon  which  the  trolley  pole 
swivels,  and  which  furnishes  the  tension  that  holds  the  trolley  wheel 
against  the  wire,  is  designed  to  maintain,  hy  means  of  springs,  an 
approximately   even   tensidn   against   the   trolley   wire,    whether  the 


Fig.  HS.    Trolley  Base. 

troUev  wire  is  high  aho\e  the  track  or  near  the  car  I'oof.  This  is 
done  hy  changing  the  relative  leverage  which  the  springs  of  the 
trolley  hase  have  on  the  trolley  pole  according  to^the  height  of  the 
trolley  pole. 

Fig.  38  shows  one  form  of  trolley  base.     The  trolley  base  is 

bolted  to  a  platform  constructed 
for  it  on  the  roof  of  the  car;  and 
the  supply  wire  to  the  motors  and 
other  electrical  devices  on  the  car, 
except  in  cases  where  a  wooden 
trolley  pole  is  used  for  certain 
special  reasons,  is  connected  di- 
rectly to  the  trolley  base.  An  in- 
sulated trolley  wire  is  run  down 
the  wooden  trolley  })ole,  and  con- 
nected through  a  flexible  lead  to 
the  car  wiring. 

Trolley  Poles.  The  trolley  poles  in  general  use  are  of  tubu- 
lar steel,  which  gives  the  greatest  strength  for  a  given  weight,  and 
which  can  usually  be  straightened  if  the  pole  has  been  bent  by  striking 
overhead  work  when  the  trolley  wheel  leaves  the  wire. 

Trolley  Wheels.  Trolley  wheels  are  from  four  to  six  inches 
in  diameter  over  all,  the  small  wheels  being  used  in  the  city  service, 
and  the  large  wheels  in  high  speed  interurban  service.  A  typical 
trolley  wheel  is  shown  in  Fig.  .'>9.     A'arious  com])anies  use  various 


Fig.  Kt.    Trolley  Wheel. 


ELECTRIC    RAILWAYS 


45 


forms  of  groove  in  the  trolley  wheels,  some  adopting  a  groove  approxi- 
mately V-shape<l.  The  U-sha[)e(l  groove,  however,  is  the  most 
common.  The  trolley  wheel  is  made  of  a  brass  com})osition  selected 
for  its  toughness  and  wearing  ((ualities. 

Trolley   Harp.     The  trolley  harp,  which  is  placed  on  the  end 


Fig.  -10.    Trolley  Harp. 


of  the  trolley  pole  and  in  which  the  trolley  wheel  icvolvcs,  usually 
has  some  means  for  making  electrical  contact  with  the  wheel  in 
addition  to  the  journal  bearing.  In  the  harp  illustrated  in  Fig. 
40,  which  is  a  typical  form,  this  additional  contact  is  secured  by  a 
spring  bearing  against  the  side  of  the  hub  of  the  wheel. 

Since  trolley  wheels  re- 
volve at  a  very  high  speed,  some 
unusual  means  of  lubrication 
must  be  provided,  since  there 
is  no  opportunity  for  ordinary 
oil  or  grease  lubrication. 
Graphite,  in  the  shape  of  what 
,is  called  a  "graphite  bushing," 
is  most  commonly  used.  This 
is  a  brass  bushing,  w^hich  is 
pressed  into  the  hub  of  the 
trolley  wheel.     In  this  bu.shing 

is  a  spiral  groove  filled  with  graphite  which  is  supposed  to  furnish 
sufficient  lubrication  as  the  bu.shing  wears.  Roller-bearing  trolley 
wheels  have  been  used  to  a  limited  extent,  with  considerable  success 
in  .some  cases.  Some  companies  have  done  away  with  the  graphite 
bushing,  and  have  provided  a  very  long  journal  for  the  trolley  wheel 
instead  of  the  usual  short  bu.shing. 

Contact   Shoes.      The  contact  .shoe   most  commonly  used  on 
roads  employing  the  third  rail  is  .shown  in  Fig.  41.     This  is  simply 


Fit'.  41.     Third  Kail  Shoe. 


46 


ELECTKTC    RAILWAYS 


a  shoe  of  c-ast  iron  hung  loosely  hv  links.  The  weight  of  the  shoe 
is  sufficient  to  give  contact,  'i'he  motion  of  the  links  permits  the 
shoe  to  acconnnodate  itself  to  unusual  obstructions  and  variations 
in  the  height  of  the  third  rail.  The  shoe  is  fastened  to  the  truck 
frame  l)v  means  of  a  wooden  plank  which  furnishes  the  necessary 
insulation. 

The  Potter  third-rail  shoe  which  has  been  u.sed  to  a  limited 

extent,  employs  a  spring  for  giving  the  nec- 
essary tension  to  make  electrical  contact 
between  the  shoe  antl  the  third  rail.  In 
some  ways  this  is  superior,  because  a  spring 
tension  is  cjuicker  in  its  action  than  gravity, 
and  the  shoe  acconnnodates  itself  better  to 
variations  in  the  height  of  the  third  rail  at 
very  high  speed.  The  wear  on  the  shoe, 
however,  is  likely  to  be  greater. 

Sleet  on  Trolleys  and  Third  Rails. 
The  (le;j:)osit  of  sleet  on  trolleys  and  third 
rails  hinders  greatly  the  operation  of  cars. 
Often  sleet  wheels  of  the  type  shown  in 
FiiT.  42  are  used  as  a  trollev  wheel.  These 
cut  the  sleet  off  instead  of  rolling  over  it. 

On  the  third  rail,  scrapers  and  brushes  in  advance  of  the  contact 
shoe  are  usually  effective  where  trains  are  frecjuent.  Several  roads 
are  now  melting  the  sleet  on  the  rails  by  the  use  of  a  solution  of  calcium 
chloride.  The  solution  is  stored  in  a  tank  on  the  car  and  is  led  through 
small  pipes  to  the  rail  innnediately  in  front  of  the  collecting  .shoe. 
About  one  gallon  of  solution  is  used  per  mile,  making  the  co.st  about 
7V  cents  i)er  mile.  The  effects  of  one  treatment  last  for  two  or  three 
hours  during  the  continuance  of  a  storm. 

Solutions  of  common  salt  have  been  used  in  the  same  manner, 
but  it  is  claimed  that  the  corroding  action  on  the  iron  of  the  calcium 
cliioride  is  not  as  great  as  that  of  a  salt  solution. 

TRUCKS. 


Fiar.  -Ji.     Sleet  Wlieel. 


Electric  railway  cars  arc  classified  generally  as  (lotiblc-frurk  and 
isincjlc-truck  cars.     Uouble-truck  cars  are  those  that  have  a  truck 


M 


48  ELECTRIC    RAILWAYS 


that  swivels  ;it  radi  end  of  tlic  ear.  A  sinj^le-tnick  car  is  one  having 
four  wheels. 

Single  Trucks.  A  ij^reat  many  types  of  sin}i;le  trueks  have 
been  (lesi<fne(l.  It  would  .be  out  of  the  (juestion  to  diseuss  theui 
all  here.  In  general,  however,  it  may  be  said  that  truek  builders 
have  aimed  to  make  a  truek  frame  in  itself  a  complete  unit  inde- 
pendently of  the  car  body,  so  that  the  car  body  will  simply  rest 
upon  the  trucks  and  there  will  be  no  .strain  on  the  car  body  in  main- 
taining the  alignment  of  the  truek.  ^lost  single  trucks,  therefore, 
consist  of  a  rectangular  steel  frame,  either  cast  or  forged,  riveted 
or  bolted  together.  This  frame  holds  the  journal  i)o.\es  in  rigid 
alignment.  I  sually  a  spring  is  placed  between  each  journal  box 
and  the  truck  frame.  This  spring  may  be  either  spiral  or  elliptic. 
The  principal  sj)rings,  however,  are  between  the  truck  frame  and  the 
car  body.  Most  truck  builders  have  used  a  combination  of  spiral 
and  elliptic  springs  between  the  car  Ixnly  and  truck  frame,  as  this 
combination  is  considered  to  give  better  riding  (pialities  and  greater 
freedom  from  teetering  or  galloping  than  either  spiral  or  elliptic 
.springs  alone.  Fig.  43  shows  a  Brill  single  truck,  which  illustrates 
all  of  the  features  enumerated. 

Swivel  Trucks.  Swivel  trucks,  commonly  called  doiihlc  fniclcs, 
are  made  in  many  forms,  but  the  mo.st  common  is  that  known  as  the 
]\L  C.  B.  type  of  truck.  This  truck  is  similar  to  the  standard  truck 
which  is  in  universal  use  on  steam  railroad  passenger  cars  in  the 
United  States.  Different  truck  builders  have  introduced  manv  varia- 
tions  in  this  general  type  of  truck,  in  adapting  it  to  electric  service. 
Some  modifications  from  the  steam  railroad  standard  truck  were 
necessary  to  accommodate  the  electric  motors  and  to  permit  in  some 
cases  a  low-hung  car  bodv.  Such  trucks  are  made  in  a  great  varietv 
of  sizes. 

Fio;.  44  .shows  one  of  these  trucks  built  bv  the  St.  Louis  Car 
Company.  Tn  this  type  of  truck  the  car  body  is  fastened  to  the 
truck  only  by  the  kingi^olt  on  which  the  truck  swivels.     This  kingbolt  \ 

is  placed  in  the  center  of  the  truck  ])olster.  There  are  also  side 
bearings  between  the  car  body  and  the  ends  of  the  bolster,  to  prevent 
ti])ping  of  the  car  body  when  it  is  unbalanced.  The  arrangement 
of  this  part  of  the  truck  is  shown  in  Fig.  45.  Under  this  bol.ster  are 
elliptic  springs  which  rest  on  what  is  called  the  sprinc/  plank:     This 


ELECTRIC    RAILWAYS 


49 


Fit;,  u.    St .  Louis  Car  Company  Truck. 


spring   plank  i.s  Imng 
from    tlie    roctan«^nliir 
frame  of  tlio  truck  by 
liiik.s    whic'li    allow   a 
aide  motion.      This 
side  motion  pves  ea.s- 
ier    riding,    e.sj)ecially 
upon    entering    and 
leaving   curves.     All 
tru(dvs    having    this 
feature  are  known   as 
su-'dkj  holster  Irucks. 
The    weight,    being 
transmitted    to    the 
transom    and    tru(d<. 
frame    through    the 
swinging  links  just 
referred  to,  is  tlien 
taken  by  the  ecjualizer 
springs    that    support 
the   rectangular  truck 
frame    on    erjualizing 
bars,  which  ecjualizing 
bars  rest  on  the  jour- 
nal box  at  either  end 
and  are  bent  down 
to     accommodate    the 
ui^rings  located  be- 
tween   them    and  the 
truck    frame.      'J'he 
truck  frame  holds  the 
journal  boxes  in  align- 
ment  by   means   ot 
guides  which  permit  an 
up-and-down  move- 
ment   without    move- 
ment in  anv  other  di- 


50 


ELECTRIC    RAILWAYS 


rectioii.  just  as  on  all  other  types  of  truck.  It  is  thus  seen  that  there 
are  two  sets  of  springs  between  the  car  Ixxly  and  car  journals;  one 
set  of  spiral  sprin<^s  l)etween  tlic  e(|uali/.in<;  har  and  truck  frame; 
and  one  set  <»f  elliptic  sjjrini^s  between  the  spring   plank   and  the 


/</ng  bo/f 


i^ 


,Bo/sfer  SZX       Transom 
(°)      !l    '~ 


-^ 


•Spr/n^  p/ank 
Fig.  45.    nolster.  Thinks  and  Spring  I'laiik 


bolster.  All  siiocks  luust  be  transmitted  first  through  the  spiral 
.springs  and  then  through  the  elliptic  springs.  Tiie  motors  u.sed 
on  this  ty})e  of  truck  usually  have  nose  susj)ension,  tlie  no.se  of  the 
motor  resting  eithcn*  on  the  bolster  of  the  truck  or  on  the  truck  frame. 


Fig.  46.    .Stool  Tire  Wheel. 


There  are  a  number  of  swivel  trucks  made  which  have  departed 
con.sideral)ly  from  ]M.  C.  B.  lines,  but  nearly  all  retain  the  features 
of  a  bolster  mounted  by  springs  on  a  spring  plank,  a  spring  plank 
hung  from  a  transom,  a  transom  rigidly  fastened  to  the  rectangidar 
truck  frame  of  which  it  forms  a  part;  and  a  truck  frame  with  one 
or  more  sets  of  spiral  springs  between  it  and  the  journal  boxes. 


ELECTRIC    RAILWAYS 


51 


Maximum  Traction  Trucks.  A  type  of  swivel  truck  tluit 
once  was  very  popular  hut  has  largely  heen  superseded  hy  the  type 
just  descrihed  is  the  "maximum  traction  truck."  This  truck  has 
two  large  wheels  on  an  axle  which  carries  GO  to  70  per  cent  of  the 
weight  on  the  truck,  and  two  small  wheels  carrying  the  balance 
of  the  weight.     The  motors  are  on  the  large  wheels. 

Car  Wheels.  The  car  wheels  most  commonly  used  are  of 
cast  iron.  In  order  to  make  a  tread  and  flange  upon  which  the  wear 
comes,  hard  enough  to  give  a  good  mileage,  the  tread  and  flange  are 
chilled  in  the  process  of  casting.  Around  the  periphery  of  the  mould 
in  which  the  wheels  are  cast,  is  a  ring  of  iron  instead  of  the  usual 
sand.  When  the  molten  cast  iron  comes  in  contact  with  this  ring 
of  iron,  which  is  called   a  '^  chill,"  the  iron  is  cooled  so  suddenly 


T 

J;. 


krtrl 


Tf 


i^ - 


%fQl 


^  ^^.^^2• 


-// 


/" 


1    \ 


'■//v//,///A 


4. 


h— - — 


76' 


-46 


^7-; 


K. 


1- 


TT-t 


'J 
1 


86 A 


Fig.  47.    Elevated  Car  Axle. 


that  it  becomes  extremely  hard.  The  balance  of  the  wheel,  cooling 
more  slowly  since  it  is  surrounded  by  sand,  has  the  hardness  of 
ordinary  cast  iron.     A  steel  tire  wheel  is  shown  in  Fig.  40. 

^Yheels  with  steel  tires  are  coming  into  use  for  elevated  and 
interurban  cars  because  their  flanges  are  not  so  brittle  as  those 
of  cast-iron  wheels.  In  wheels  of  cast  metal  there  is  always  a 
liability  that  the  flanges  and  tread  will  chip  and  crack.  On  high- 
speed cars  the  falling-out  of  pieces  of  flange  may  be  a  serious  matter 
and  result  in  a  wreck.  Steel-tired  wheels  have  a  hub  .and  spokes 
either  of  cast  or  forwd  steel  or  iron.  On  to  this  wheel  a  steel  tire 
is  shrunk.  The  tire  is  lieated  in  a  furnace  built  for  the  j)urpose, 
and  is  then  slipped  over  the  wheel.  It  is  made  just  such  a  size 
that  it  will  slip  over  the  wheel  when  hot,  and  when  it  is  cool  it 
will  shrink  enough  to  make  a  very  tight  fit.  When  the  tire  is  to  be 
removed  after  it  is  worn  out,  it  is  heated  until  it  has  expanded  suffi= 
ciently  to  drop  off. 


M 


ELECTRIC    RAILWAYS 


An  axle  for  eleviited  car  is  sliown   in   Fij^.  47. 

Wlioii  cast-iron  wheels  are  worn  to  an  inijn-oper  sliape  or  liave 
flat  spots  npon  thcni,  dne  to  the  sli(lin<i;  of  the  wheels  with  the  brakes 
set,  an  emery  wheel  n;nn(ler  nmst  be  used  to  grind  them  down, 
as  nothint;  else  is  hard  enon<di  to  have  any  elTect  on  the  iron. 

D/ame/er  of  ch/7/rno/c/s    for   33" 
whee/s  fo6e   33j"   for  30"  whee/s 
fo  he  30g   measured  on  //neA-B 


Fig.  48.    Standard  M.  C.  IJ.  Flange. 

When  steel-tired  wheels  are  worn,  they  can  be  pnt  in  a  lathe 
and  the  snrface  of  the  tire  tnrned  olf,  as  this  snrface  is  of  metal  soft 
eirou<:;h  to  be  work<U)le  witli  ordinary  tools. 

The  types'  of  wheel  tread  and  wheel  flanf^e  in  use  vary  greatly 
among  different  electric  railways.     There  is  a  standard  ^Master  Car 


Fig.  10.    UraltP  Shops  and  r.,»n-('rs. 

Rnilders'  wheel  tread  used  on  steam  railroads,  which  is  shown  in 
Fig.  4S.  Electric  railways,  however,  are  n.snally  obliged  to  use 
a  smaller  flange  and  narrower  tread.  Street  railway  special  work, 
such  as  switches  and   cro.ssings,   usnallv  has  too   .shallow   a   flange 


LUi^v 


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Z 

u 
ou 


Of 

d 

u 

O 

V 

CO 

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o 

'^ 

^ 

u 

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iC 

< 

< 

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ce 

3 

CQ 

O 

a 

tc 

to 

1> 


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s 

o 

H 

< 


ELECTKIC    KAILWAYS 


53 


a 


wav  to  permit  a  staiulard  M.  ( '.  B.  Ilaiiue  to 
j)ass  through.  Some  street  raihvays  use  flanges 
as  sliallow  as  ^-incli,  althougli  ]-inch  is  most 
common  on  citv  work.  The  width  of  tlie  tread 
on  street  railway  cars,  that  is,  tlie  width  of  the 
wheel  where  it  bears  on  the  rail,  is  usually  from 
If  inches  to  2j  inches.  There  is  a  tendency, 
however,  on  electric  railways,  on  account  of 
the  increasing  number  of  interurban  cars  which 
nnist  use  city  tracks,  to  Iniild  tracks  that  will 
accommodate  wheels  approaching  the  INI.  C.  B. 
standard  of  steam  roads.  A  few  roads  have 
adopted  wheel  treads  and  flanges  very  near 
to  the  :\I.  C.  B.  standard. 

Brake  Rigging.  The  brake  rigging  on 
a  single-truck  car  may  be  arranged  in  a 
variety  of  ways,  but  should  be  sucli  that  a 
nearly  equal  pressure  will  ]>c  brouoht  tol)ear 
on  the  brake  shoes  on  all  four  wheels.  A 
typical  arrangement  of  brake  shoes  and  levers 
for  single-truck  cars  is  shown  in  Fig.  40.  The 
rods  R  terminate  in  chains  winding  around 
the  brake  staff  upon  which  the  motorman's 
handle  or  hand  wheel  is  mounted. 

For  double-truck  cars  the  brake  rigging 
is  necessarily  more  complicated,  as  it  must 
be  arranged  to  give  an  equal  pressure  on  all 
eight  wheels  of  the  car.  Brake  shoes  are 
sometimes  placed  between  the  wheels  of  a 
truck  and  sometimes  outside.  The  arrange- 
ment of  brake  shoes  between  wheels  is  appar- 
ently finding  most  favor,  ,as  when  the  shoes 
are  applied  in  this  position  there  is  less  tend- 
ency to  tilt  the  truck  framt>  when  the  brakes 
are  applied,  and  this  adds  to  the  comfort  of 
passengers  in  riding.  Fig.  !^0  shows  one  form 
of  arrangement  of  brake  levers  common  on  a 


ELECTRIC    liAlLWAYS 


doulde-tiufk  car  ('(jiiijiped  witli  air  Urakes.  witli  iiisi(le-luino| 
Itrake  slioes. 

Brake  Leverages  and  Shoe  Pressure.  The  levers  between 
the  air  cylinder  and  the  ])rake  shoes  are  usually  so  proportioned  that 
with  an  air  jiressureol"  70  11)S.  per  S(p  in.  in  the  brake  cylinders  the 
total  of  the  brake  shoe  pressures  on  the  wheels  will  be  equal  to  about 
'.to  ])ercentof  the  weight  of  the  car.  The  dian-rani  F'm.  51  has  shoe 
j)ressures  and  strains  in  the  several  rods  marked  on  shoes  and  rods. 

The  following  example,  based  on  the  diagram,  will  explain 
the  lever  proportioning.  Only  round  numbers  are  given  on  the 
diacrram. 

Assume  a  four-motor  car  weighing  40.000  pounds.  A  brake 
cylinder  7 inches  in  diameter  is  used.  This  gives  H8.5  square  inches 
and  at  70  pounds  air  pressure  a  total  force  on  the  piston  rod  of 
2,695  pounds.  The  weight  of  the  car  is  40,000  pounds.  Taking 
00  per  cent  of  this  gives  a  total  of  36,000  pounds  to  be  exerted  by 
the  brake  shoe  when  an  emergency  stop  is  made.  Each  of  the 
eight  shoes  will  press  against  the  wheels  with  a  force  of  4,500 
])()unds. 

The  dimensions  of  th(^  ti'uck  are  such  that  the  "dead  levers," 
those  lixed  at  one  end  and  which  carry  shoes,  cannot  be  over  18 
inches  long.  The  shoe  will  be  hung  three  inches  from  one  end. 
making  the  proportions  10  to  8,  and  the  pressure  on  the  strut  rod 
between  shoes  will  be  4,500  X  \l  or  3,  461  pounds.  To  clear  the 
truck  frame  the  live  lever  extends  14  inches  above  the  point  of 
application  of  the  brake  shoe.  To  obtain  4,5()0  pounds  pressure 
on  the  shoe,  the  distance  between  the  brake  shoe  and  the  strut 
rod,  which  we  will  call  "a*,"  will  be  found  by  regardinca-  the  U])T)er 
end  of  the  lever  as  iixed  and  the  power  applied   at  the  lower  end. 

14  +  rr 
4500  =  3461  X         ^      or 

X  =  4,2  inches. 

Now  to  obtain  the  force  required  in  the  rod  to  the  truck  quad- 
rant, the  bottom  end  of  the  live  lever  must  l)e  reofarded  as  the 
fulcrum.      The  equation  is 

X  =  4500  X  |7TT)    =  10.38  pounds. 


ELECTRIC    RAILWAYS 


55 


As  the  pull  rods  from  each  side 
of  the  truck  are  attached  to  the 
truck  ([uadrant,  the  stresses  iu 
the  ])rake  rods  are  double  this,  or 
2,076  pounds. 

The  position  of  the  brake  cyl- 
inder under  the  car  restricts  the 
length  of  the  "live"  and  "dead" 
cylinder  levers  to  Hi  inches.  To 
obtain  2,076  pounds  pull  on  one 
end  of  the  levers  with  the 
previously  computed  2,695  pounds 
on    the    other,    the    proportions 

2076  X       . 

must  be    f-^^'  =  TTT?  since 

2076  +  2695  ---  4771.  Then  x 
=  7  inches,  the  distance  from  the 
brake  piston  to  the  pivotal  point. 

Since  2,695  pounds  pressure  is 
exerted  and  36,000  poiuids  results 
the  proportion  of  the  whole  system 
of  levers  is  36,000  to  2,695  oi-  13.3 
to  1.  In  other  words  the  travel 
of  the  piston  in  the  cylinder  will 
be  13.3  times  that  of  the  shoes  if 
there  were  no  lost  motion  to  be 
taken  up.  The  piston  travel 
should  be  from  4  to  5^j  inches. 
This  gives  about  |-inch  travel  of 
the  brake  shoes.  Increased  travel 
of  the  brake  shoes  necessary  to  set 
them  as  they  wear  away  causes 
increased  travel  of  the  piston  of 
the  air  cylinder.  Not  only  is 
more  air  used  at  each  application 
of  the  l)rakes  l)ut  the  brakes  are 
slower  in  acting.     It  is  therefore 


56  ELECTKIC    RAILWAYS 

necessary  to  luljust  the  brakes  frecjuently.  This  is  done  in  the  sys- 
tem shown  in  the  diagram  hy  the  use  of  a  turnl)iic'kle  in  the  con- 
necting rod  between  tlie  hve  and  dead  levers  of  the  truck. 

When  two  motors  arc  on  one  truck  and  none  on  tlie  other, 
allowance  must  l)c  made  in  the  levers  for  the  increased  weight  of 
the  motor  truck  and  the  inertia  of  the  armature.  The  leverage 
on  the  motor  truck  nuist  be  greater  than  on  the  other. 

Air  Brakes.  Air  brakes  used  on  electric  railway  cars  are 
usually  of  what  is  called  the  straight  air  brake  type  in  distinction  to  the 
Wesiinghouse  automatic  air  J>rake.  A  straight  air  brake  is  one  in 
which  the  air  is  stored  in  a  reservoir;  and,  when  the  brakes  are  to  be 
applied,  air  from  this  reservoir  is  turned  directly  into  the  brake 
cylinder,  in  which  works  a  piston  operating  the  brake  lever^-.  Air 
admitted  behind  the  piston  forces  it  out  with  a  pressure  which  applies 
the  brakes.  When  the  air  is  let  out  of  the  brake  cylinder,  a  spiral 
spring  forces  the  piston  back  to  its  original  position  and  the  brakes 
are  released.  The  motorman's  valve  by  which  he  applies  the  brakes, 
therefore,  provides,  first,  for  turning  air  from  the  storage  reservoir 
to  the  brake  cylinder  to  apply  the  brakes,  and,  second,  for  closing 
the  opening  to  the  storage  reservoir  and  opening  an  exhaust  passage 
from  the  brake  cylinder  so  that  the  air  can  escape  from  the  brake 
cylinder  to  release  the  brakes. 

Straight  air  brakes  of  this  kind  would  not  be  suited  to  the  opera- 
tion of  long  trains,  because,  if  the  air-brake  hose  connection  l)etween 
cars  should  be  broken,  the  brakes  would  be  useless;  but  for  trains 
of  one  or  two  cars,  such  as  are  common  in  electric  railway  practice, 
the  simplicity  of  the  straight  air  brake  outweighs  its  disadvantages 
and  this  is  the  type  of  brake  usually  employed.   (See  Fig.  52.) 

The  Westinghouse  and  other  forms  of  automatic  air  l)rake  are 
used  on  electric  railways  where  cars  are  operated  in  long  trains; 
but  it  is  out  of  the  province  of  this  })aper  to  describe  these  brake 
systems  fully,  as  they  arc  rather  complicatcMl.  Tt  may  be  said  in 
general,  however,  that  the  Westinghouse  automatic  air  brake  is  so 
arranged  that,  should  the  hose  connection  between  cars  be  broken, 
shoidd  the  train  ])nll  in  two,  or  should  anything  happen  to  reduce 
the  pressure  which  is  maintained  in  the  train  ]Mpe  that  runs  the 
length  of  the  train,  the  brakes  would  immediately  be  applied  on 
the  entire  train. 


ELECTRIC    RAILWAYS 


57 


&^, 


puno-i^  ql 


K 


Compressors.     A  small  air  coinpresscr 
driven  by  an  electric  motor  is  frequently 
employed    on    electric    cars  to  keep    the 
storage  reserv'oir  of  the  car  sup])lied  with 
air.     These   air  compressors   are  carried 
under  the  car  or  in  the  motorman's  cai). 
They  are  generally  arranged  with  an  auto- 
matic   device    which    closes    the    motor 
circuit  and  starts  the   motor  as  soon  as 
the    air    pressure    falls    below    a   certain 
amount;  and  the  motor  will  continue  in 
operation  pumping  air  until  the  pressure 
rises  to  the  amount  for  which  the  auto- 
?     matic  device  is  set.     The  pressure  carried 
.£-     in  the   storage    reservoir  is  usually  from 
$     GO  t;)  90  pounds  per  square  inch,  \vhich, 
:^     as  a  general  thing,  is  considerably  more 
than  is  required  to  apply  the  brakes  hard 
enough  to  slide  the  wheels. 

Automatic  Governor  for  Air  Com= 
pressors.  Automatic  governors  are  often 
installed  in  connection  with  air  compress- 
oi-s  in  order  that  a  fairly  even  air  pressure 
may  be  maintained  in  the  storage  reservoir. 
In  these  the  fall  and  rise  of  the  air  pres- 
sure within  certain  limits  closes  and  opens 
the  circuits  to  the  motor.  In  some  styles 
the  air  acting  on  a  piston  operates  the 
circuit  breaker. 

The  diagram  shown  in  Fig.  53  shows 
the  principleof  the  Christensen  governor., 
in  which  the  air  pressure  is  employed 
lo  make  and  break  a  secondary  circuit. 
^Vhen  the  pressure  in  the  storage  res- 
ervoir falls  below  a  predetermined  value, 
the  hand  of  the  air  gauge  makes  con- 
tact with  lug  A.  This  closes  tl:c  circuit 
through  solenoid  Xo.  1.     Lug  l),nicchau- 


U 


58 


ELECTKIC   KAILWAYS 


ically  connected  to  the  armature  of  the  solenoids  is  pulled  in  con- 
tact with  lug  (\  and  this  closes  the  circuit  to  the  motor,  and 
shunts  the  winding;  of  solenoid  No.  1.  Wlicn  the  air  pressure  rises 
to  a  predetermined  value  the  hand  of  the  air  gauge  is  thrown  in 
contact  with  lug  B.  This  energizes  solenoid  2  ])y  connecting  it 
across  the  motor  terminals.  The  armature  is  pulled  to  the  right 
and  the  circuit  to  the  motor  is  broken.  ^Vhen  this  is  done  it  is  evident 
that  the  current  through  the  energized  solenoid  is  broken.  It  is 
evident  from  the  descrij)tion  that  current  j)asses  through  the  .solenoids 


Trolley 


i 


K 


Solenoid    I 


D 


^ 


c 


Compresso, 
Motor 


Fields 


Ground 
Fig.  oH. 


K 


K 


Solenoid     H 


onlv  during  the  .sfiort  j)erio<is  that  the  armature  is  moving  from  one 
position  to  the  other  and  the  air  gauge  never  has  to  break  a  circuit 
in  which  there  is  an  appreciable  voltage  so  that  there  is  no  arcing  at 
lugs  A  and  B. 

A  blow-out  coi.  m  series  with  the  motor  .s  provided  innnediately 
under  lug  C  which  extinguishes  the  arc  at  that  point  when  the  motor 
circuit  is  broken. 

A  Westinghouse  air  compressor  is  .shown  in  Fig.  7A. 

Storage  Air  Brakes.  The  storage  air-brake  system  does  n(»t 
have  a  .small  inde|)e:;!dent  compressor  on  each  car,  but  ia  c(|uipped 
with  a  large  .storage  tank,  in  which  air  is  carried  under  high  ])res- 
sure — 250  t(j   ijOO   pounds   p«er  .scjuare   inch.     This  .storage  tank  is 


ELECTRIC    RAILWAYS 


59 


filled  at  regular  intervals  when  the  car  passes  some  point  on  its 
route  at  which  a  compressor  is  located.  In  this  case  the  car  is 
obliged  to  stop  long  enough  to  make  connection  to  the  tank  of  the 
ccmipressor  plant,  and  to  allow  the  car  storage  tank  to  be  filled. 
This  operation,  however,  does  not  take  long.  The  advantages  of 
the  system  are  a  saving  of  the  weight  and  a  saving  in  the  mainte- 
nance of  a  small  compressor  on  each  car.  From  the  main  storage 
tank  under  the  car,  air  is  led  through  a  reducing  valve  to  an  auxiliary 
storage  tank.  This  reducing  valve  allows  enough  air  to  pass  through 
to  maintain  a  pressure  of  about  50  pounds  per  scjuare  inch  in  the 


Fig.  bi.     Wcstiiighoiise  Air  Compressor. 


auxiliary  storage  tank.  The  auxiliary  storage  tank  corresponds  to 
the  regular  storage  tank  on  a  system  employing  compressors  on  each 
car.  The  method  of  operation  after  the  air  has  entered  the  auxiliary 
storage  tank  is  the  same  as  with  any  air-brake  system. 

Fig.  55  shows  the  arrangement  of  the  apparatus  under  the  cars 
of  the  St.  I.<ouis  Transit  rom})any.  The  two  storage  tanks  are 
each  G  feet  long  by  18  inches  in  diameter  and  are  mounted  one  on 
each  side  of  the  car.  Their  combined  capacity  is  equivalent  to  about 
100  cubic  feet  at  45  lbs.  pressure.  The  tanks  are  charged  through 
an  outlet  near  one  side  of  the  car.  This  outlet  contains  a  check 
valve  and  cock  to  prevent  leakage. 

The  service  or  low  pressure  reservoir  has  a  capacity  of  about 
2j  cubic  feet.  The  position  of  the  reducing  valve  between  ihe  high 
and  low  pressure  valves  may  be  noted  in  the  illustration. 

Momentum  Brakes.  jNIomentum  or  fi'iction  brakes  have  been 
used  to  some  extent  both  on  single-truck  and  on  (h)uble-truck  cars. 


60 


ELECTKIC    KAIL  WAYS 


but  purticulurly  on  .siii<i;U'-tnK-k  cars.  They  derive  the  jx)\vej'  to 
operate  the  brakes  from  the  nionientuin  of  the  car  by  means  of 
a  friction  chitch  on  tlic  car  axle.  The  (Utference  in  various  kinds 
of  momentum  l)rakes  lies  chiefly  in  the  desit^n  of  the  clutch  mech- 
anism. Hie  clutcii  must  evidently  be  urrani^etl  to  act  verv  smoothly, 
and  must  be  uniler  very  accurate  control,  as  tiie  force  with  which 
the  brakes  are  applied  depends  directly  upon  the  pull  exerted  by 
the  clutch. 


'-^-  ^1^^^^  j>LL----  -_-.  ^  -_4  4  ^  -^  J-.  i!-Sij| 


^-  Charging  Coupling 
Fig.  .55.    Arrangement  of  Storage  Air  Brake  Apparatus. 

Ill  the  Price  momentum  brake  a  Hat  tlisc  is  cast  on  the  car 
wheel,  which  is  turned  off  to  a  smooth  surface.  Against  this  disc 
a  friction  clutch  acts,  which  has  a  leather  face.  The  clutch  is  operated 
bv  a  motorman's  lever  through  a  .set  of  levers.  A  small  movement 
in  the  motorman's  lever  forces  the  clutch  against  the  disc  on  the 
car  axle.  The  clutch  winds  up  the  brake  chain,  and  thus  supj)lies 
power  to  apply  the  brakes. 

Other  momentum  or  friction  clutch  iirakes  have  been  devi.sed, 
most  of  which  also  use  an  application  of  Jeather  on  iron  for  the  clutch, 
as  this  has  been  found  to  be  most  reliable,  and  to  be  least  affected 
bv  the  irrease  and  dirt  that  is  liable  to  work  in  l>etween  the  clutch 


SI 


u-fac 


•es. 


ELECTRIC    RAILWAYS  61 


Q.  E.  Electric  Brake.  The  (Teneral  Elective  i^ompany's  elec- 
tric brake  makes  use  of  current  generated  by  the  motors  actmg  as 
dynamos,  to  stop  the  car.  In  N)rder  to  accomplish  this,  a  brake 
controller  is  provided  which  reverses  the  armature  connections  of 
the  motors,  and  so  ?onnects  them  to  operate  as  dynamos  sending 
current  +Jirough  a  resistance  in  the  circuit;  the  amount  of  current 
flowing  and  the  braking  eflect  depending  on  the  car  speed  and  the 
resistance  In  some  forms  of  brake  controller,  the  two  controllers 
are  ccmibined  in  one  cylinder,  so  that  the  motorman,  to  apply  the 
electric  brake,  simply  continues  the  movement  of  the  handle  past 
the  "off"  position.  In  others,  the  brake-controller  drum  is  sep- 
arate, but  is  interlocked  with  the  main  controller  so  that  it  can  be 
used  only  when  the  main  controller  is  off. 

However  the  controller  may  be  arranged,  the  principle  in- 
volved is  that  when  the  motors  are  revolving  by  the  motion  of  the 
car,  and  the  armature  connections  are  reversed  as  they  woidd  be  to 
reverse  the  direction  of  motion  of  the  car,  the  motors  begin  to  generate 
current  as  series-wound  dynamos.  The  amount  of  current  generated 
and  the  retarding  effect  will  depend  on  two  things — namely,  the 
speed  of  the  car,  with  the  consequent  electromotive  force  in  the 
motors,  and  the  amount  of  resistance  in  the  circuit.  The  amount 
of  resistance  is  regulated  by  the  motorman  by  means  of  his  electric 
brake  controller.  The  function  of  the  electric  brake  controller  is 
to  reverse  the  motors  and  to  insert  enough  resistance  in  the  circuit 
to  make  a  comfortable  stop.  This  current  in  the  motors  acting  as 
dynamos,  in  itself  acts  as  a  powerful  brake  to  retard  the  motion  of 
the  car.  In  the  General  Electric  type  of  electric  brake,  the  current 
generated  in  the  motors,  in  addition  to  having  this  retarding  effect 
in  the  motors  themselves,  is  conducted  to  brake  discs  that  act  as 
magnetic  clutches  against  one  of  the  car  wheels  on  each  axle.  The 
car  wheel  has  a  disc  cast  upon  it,  and  against  this  the  magnetic  disc 
acts.  The  magnetic  disc  contains  a  coil  which  is  in  series  in  the  brake 
circuit. 

In  applying  an  electric  brake  of  this  kind  Uic  motorman  first 
puts  the  controller  on  a  point  that  inserts  considerable  resistance 
in  the  circuit.  When  the  motors  have  slowed  down,  the  electromo- 
tive force,  of  course,  drops,  so  that  to  maintain  the  same  braking 
current  thcie  iinist  be  a  reduction  of  the  amount  of  resistance,  until, 


G2 


ELECTRIC    RAILWAYS 


wlion  the  car  is  uliuost  at  a  .standstill,  the  resistanee  is  nearly  all  cut 
out.  It  niiijht  .seem  at  first  that  the  current  would  die  down  hefore 
the  car  came  to  a  .stop,  but  it  is  found  that  there  is  enough  induction 
in  the  motor  fields  to  cau.se  current  to  flow  for  a  .short  time  after  the 
car  has  stopped.  The  residual  magnetism  in  the  .steel  in  the  fields 
of  the  motor  is  sufficient  to  cau.se  the  motors  to  begin  to  generate 
current  when  the  electric-brake  controller  is  first  turned  on. 

The  greatest  advantage  of  an  cU'ctric  l)rakc  using  motors  as 
generators  is  in  the  fact  that  the  braking  current  instantly  falls  in 
value  as  .soon  as  the  wheels  begin  to  .slide,  and  relea.ses  the  brake 


Kiir.  56.     MiiiTUflii'  Hraljc  Slio 


until  the  wheels  again  revolve.  In  fact,  it  is  almost  imj^o.ssible  to 
.skid  the  wheels  as  thev  are  sometimes  skidded  bv  l)eing  l;)cked  bv 
brake  .shoes.  This  not  only  prevents  flat  wheels  ])ut  insures  a  (juick 
.stop,  because  when  the  wheels  are  locked  and  .sliding,  the  braking 
or  retarding  power  is  only  about  one-third  what  it  was  before  the 
wheels  began  to  .slide.  The  electric  brake  requires  extra  large 
motors  because  of  the  lieating  cau.sed  by  the  current  generated 
while  braking. 

Westinghouse  Electromagnetic  Brake.  The  Westinghou.se 
magnetic  brake  is  in  ])rinciple  similar  to  the  (jencial  I'lcclric  brake 
as  far  as  the  use  of  motors  as  generators  is  concerned;  but,  instead 
of  a.s.si.sting  the  motors  l»y  means  of  a  magnetic  l)rake  di.sc  acting 
again.st  the  car  wlu'cl,  a  magnetic  l)rake  .shoe  is  u.sed  (.see  Fig.  50), 
which  acts  against  both  car  wIhh'I  and  track.     This  not  onlv  retards 


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ELECTKIC    KAILWAYS  6S 


through  the  iiie(Huin  of  the  wheels  but  acts  (Ureetly  on  the  track. 
It  is  not  dependent  upon  the  coefficient  of  friction  l)etween  the  wheels 
and  track;  and  it  should,  therefore,  be  possible  to  stop  much  more 
(jiiickly  than  with  any  form  of  brake  depending  upon  the  coefficient 
of  friction  between  the  wheels  and  track. 

Track  Brakes.  Track  brakes  have  been  used  to  some  extent 
on  very  hillv  electric  nxids.  These  have  a  shoe  fastened  to  the 
truck  frame,  which  acts  directly  on  the  track. 

Motors  as  Emergency  Brakes,  The  motors  can  of  course 
be  used  to  brake  the  car  by  simply  ir-^ersing  them  if  current  is  applied 
to  them  from  the  line.  But  in  case  the  trolley  flies  off  or  if  the  circuit 
breaker  or  the  fuse  opens  the  circuit,  or  the  supply  of  current  is  inter- 
r\ipted  for  any  other  reason,  they  may  be  used  as  brakes  by  throw- 
ing the  reverse  lever  and  moving  the  controller  handle  to  the  multiple 
position  of  a  two-motor  ecjuipment  or  by  simply  throwing  the  reverse 
lever  of  a  four-motor  equipment.  These  movements  throw  the 
motors  in  multiple  and  connect  the  fields  and  armatures  of  the  motor 
in  such  relation  that  they  can  generate  current.  One  of  the  motors 
then  acts  similarly  to  a  generator  in  a  power  house,  deriving  its  power 
from  the  momentum  of  the  moving  car  instead  of  from  an  engine,  * 
and  sends  current  through  the  other  motor  of  the  ])air  which  acts 
like  any  auxiliary  motor  trying  to  revolve  its  wheels  in  the  opj)osite 
direction  from  that  in  which  thev  are  revolving.  The  motors  of  a 
four-motor  equipment  are  permanently  connected  in  two  nuiltiple 
groups  as  long  as  the  reverse  is  not  in  the  central  position.  In  the 
two  motor  equipment  such  connections  are  not  made  until  the  con- 
troller handle  is  turned  to  the  multiple  position.  As  the  externa! 
resistance  is  beyond  the  junction  of  the  two  motor  circuits,  the  braking 
effect  is  not  increased  by  cutting  out  the  resistance. 

The  difference  in  the  residual  magnetism  of  the  fields  or  in  the 
magnetic  qualities  of  the  fields  of  the  two  motors  is  primarily  the 
cause  of  the  generation  of  the  current.  The  motors  at  first  act  in 
opposition,  but  one  of  them  generates  the  higher  voltage  and  fcrces 
a  current  through  the  other.  This  current  overcomes  the  residual 
magnetism  of  the  second  motor,  thereby  changing  its  polarity  and 
both  motors  then  act  in  series  to  send  the  current  through  the  low 
resistance  path  afforded  by  the  windings.  Any  current  passing 
increases  the  strength   of  the  fields  and   consequently  the  voltages, 


64 


ELECTRIC    RAILWAYS 


so  tliat  ahnonnal  ciirrents    are   ijeuerated  and  the  ])rakiiii:  artion  is 
f'onseciuently  severe. 

This  generating  action  does  not  take  place  before  tlie  reverse 
lever  is  thrown  because  the  connections  of  the  armatures  and  fields 
are  such  that  any  current  generated  by  reason  of  the  residual  magnet- 
ism of  the  fields,  flows  in  such  a  direction  through  these  that  this 
magnetism  is  destrove<l.  The  current  then  ceases  to  flow,  "^riiis 
cx])iains  wliv  ciUTent  is  not  generated  in  No.  2  motor  with  a  K  tyjK* 


OuterHose ' 
Cotton 


FIlc.  .">?.     I'litMiiuulii'  Sandfr. 


of  controller  during  the  change-over  period  when  it  is  short-circuited, 
or  in  e(|uipments  when  the  trolley  flies  oft'  and  the  controller  is  turne<l 
on. 

Brake  Shoes.  The  .subject  of  brake  shoes  is  of  very  little 
importance  on  the  smaller  cars  traveling  at  .slow  .speeds  and  con- 
trolled alone  by  hand  brakes.  On  the  larger  high  speed  interurban 
cars,  the  brake  .shoe  (piestion  becomes  an  important  item  because 
of  the  rapidity  with  which  they  are  worn  away.  On  such  cars  shoes 
sometimes  last  but  about  one  week.  This  means  eight  .shoes  ])er 
week  ])er  car  or  an  expense  of  about  .S4.00  per  car  per  week. 

Brake  shoes  are  usually  of  .soft  gray  cast  iron  with  in.serts  of 
steel,  although  .some  companies  use  very  hard  iron.  'Jliey  are  u.sually 
fastened  by  means  of  a  key  to  a  brake  .shoe  head  permanently  attached 
to  the  brake  rigging.  The  brake  levers  are  .so  adjusted  that  the  .shoes 
clear  the  wheels  about  ,^g-inch  when  the  brakes  are  released.     This 


ELECTlilC    RAILWAYS 


♦)5 


distance  increases  as  the  shoes  wear,  so  that  tlie  brakes  nnist  he  ad- 
justed-freqnently  to  take  up  the  slack  and  prevent  waste  of  air. 

Track  Sanders.  A  sprinkhntj;  of  sand  on  th(^  lail  increases 
wonderfully  the  adhesion  of  the  rail  and  wheel.  There  is  usually 
on  cars  some  provision  made  for  scattering  sand  on  the  rails  inime- 
diatelv  in  front  of  the  leading  wheels.  From  sand  boxes  placed 
under  the  seats  in  the  smaller  cars,  or  on  the  truck  of  the  larger 
ones,  flexible  hose  or  pipes  drop  within  an  inch  or  two  of  the  rail 
in   front  of  the  leading  wheels.     A  valve  under  the  control  of  the 


eo    0 

Fiff-  '^S-    Curves  of  T?ral<iiiK  Tests. 


10  20     0 

Seconc/s 


mot(jrman  reijulates  the  flow  of  sand  to  the  rail.  Sometimes  air 
])ressure  is  used  to  blow  the  sand  out  of  the  sand  box  into  the  hose. 
Ill  this  case  air  pressure  is  obtained  from  the  air  brake  system,  and 
an  air  valve  leading  to  the  sand  box  is  placed  in  the  motorman's 
cab.  A  section  through  a  pneumatic  sander  of  this  kind  is  shown  in 
Fig.  r)7. 

Coefficient  of  Friction.  It  has  l)een  fomid  by  experiment 
that  the  coefficient  of  friction  between  the  car  wdieel  and  rail  is  about 
25  per  cent  of  the  w^eight  on  the  wheel  when  the  rails  are  dry;  that 
is,  a  car  wheel  having  a  weight  of  2,000  pounds  upon  it  would  not 
be  able  to  exert  either  an  accelerating  or  a  retarding  force  exceeding 
25  per  cent  of  this,  or  500  pounds.  This  is  when  the  wheel  is  rolling. 
There  is  apparently  a  kind  of  locking  or  inter-meshing  of  the  rough 


66  KLECTKK^    KAILWAYS 


surfaces  of  wheel  and  rail  when  the  wheel  is  rolling,  because  it  is 
found  that  when  a  \vhe(>l  iu'irins  to  skid  or  slide,  the  coefficient  of 
friction  falls  oft'  about  two-thirds.  The  maximum  l)rakin,n'  or  re- 
tarding force  that  can  l)e  obtained,  therefore,  in  a  dry  rail,  amounts 
to  25  per  cent  of  the  weight  of  the  cai-.  If  the  rail  is  slippery  this  is 
much  reduced;  or  if  the  wheels  are  allowed  to  slide  it  is  also  much 
reduced.  If  more  retarding  force  than  can  be  obtained  through  the 
medium  of  a  wheel  rolling  on  the  rail  is  desired,  it  inust  be  obtained 
either  by  the  track  brakes  or  l^y  magnetism. 


Fit-  ^-  .Automatic  Coupler. 


Rate  of  Retardation  in  Braking.  The  rate  of  retardation 
of  cars  in  l)raking  is  usually  1  to  2  miles  per  hour  per  second.  In 
other  words  a  car  going  at  a  speed  of  40  miles  an  hour  will  usually 
be  stopped  in  40  to  20  seconds. 

The  plotted  results  of  some  l)raking  tests  (Fig.  58)  show  a  higher 
rate  of  acceleration.  These  tests  were  made  on  an  interurban  car 
weighing  about  63,000  pounds,  equipped  with  straight  air  brakes. 
Of  the  six  curves  shown,  that  giving  the  highest  rate  of  retardation 
is  No.  4.  This  shows  a  stop  from  a  speed  of  38  miles  per  hour  in 
9.^  seconds  or  a  rate  of  retardation  of  about  4  miles  per  hour  per 
second.  All  of  the  curves  shown  are  for  emergency  stops.  They 
show  about  the  highest  rate  of  retardation  that  could  be  made  with 
the  equipment. 

Drawbars  and  Couplers.  For  small  surface  cars  a  crude 
drawbar  is  usually  provided  consisting  simply  of  a  straight  iron  bar 
pivoted  under  the  car  and  ])rovided  with  a  cast-iron  pocket  near  the 
end.  A  coupling  pin  passing  through  the  pocket  of  one  coupler  and 
throuirh  a  hole  in  the  end  of  the  bar  of  the  other,  holds  the  two  cars 
together. 

The  requirements  of  a  coupler  for  heavier  cars  such  as  those 
u.sed  on  interurban  and   elevated   roads  are  more  exacting.     The 


ELECTRIC    RAILWAYS 


67 


oikIs  of  the  bars  are  usually  pivoted  un(ier  tlie  car  about  five  feet 
back  from  the  l>umper.  A  spring  cushion  intervenes  between  the 
])ivot  point  an<l  the  (h'avvbar  iieacL  The  ilhistrations,  Fio-s.  ')<)  and 
(')(),  show  the  action  of  the  Van  Dorn  Automatic  couj)lcr,  whicli  is  the 
one  used  by  all  the  elevated  lines  in  the  United  States.  The  link  is 
placed  in  one  of  the  drawbar  heads  and  the  pin  in  the  other.  As 
the  cars  come  together  the  wedge-shaped  end  of  the  link  forces  its 
way  between  the  pin  and  a  spring.  When  the  faces  of  the  drawbar 
heads  meet,  the  spring  forces  the  link  to  engage  the  })in.  The 
mechanism  is  designed  especially  to  prevent  lost  motion  between 
coupler    heads    because,    unlike   steam    railroad    drawbars,   electric 


I  r-i  I- 


fM. 


H~n  n 


#inilr^^Hfi- ^.....mmflj^ 


Fig.  60. 

car  drawbars  must  swivel  to  round  curves  and  a  great  amount  of 
play  at  the  point  of  coupling  with  swiveling  drawbars  would  allow 
the  couplers  to  ])end  under  a  pushing  strain. 

CAR   CONSTRUCTION. 

Car  Bodies.  In  cities  there  are  'three  general  types  in  com- 
mon use;  namely,  box  cars,  suited  for  winter  use  only;  open  cars, 
suited  for  summer  use  only;  and  semi-convertible  cars,  which  can 
be  adapted  to  either  summer  or  winter  use.  The  open  and  box 
cars  are  the  older  types.  The  semi-convertible  car  is  usually  pro- 
vided with  a  center  aisle,  and  cross  seats  on  each  side  of  this  aisle. 


m 


ELECTRIC    RAILWAYS 


K 


X 


u 

E 


ELECTRIC    RAILWAYS 


69 


The  windows  are  large,  so  that  they  can  be  lowered  or  raised  in 
summer  to  make  something  approaching  the  character  of  an  open 
car.  The  car  bottom,  which  forms  the  basis  for  the  entire  car 
structure,  is  constructed  with  longitudinal  sills  either  of  steel  or 
of  wood  combined  with  steel.  One  form  of  construction  employs 
as  the  main  supports  two  steel  channel  bars  extending  the  full  length 


SecTion 

Throi/^h 

Large  Post 

^howmy  Pod 


Fig.  62.    Cross-Section  of  Car  Body. 


of  the  car.  Steel  I-beams  are  sometimes  used.  \Vhere  wootl  is 
used  in  combination  with  steel  for  longitudinal  sills,  the  steel  is  usually 
in  the  form  of  flat  steel  plates  between  the  timbers.  Most  cars  s(  at 
about  one  pas.senger  ])er  foot  of  length  over  all. 

]Many  more  difficulties  are  met  in  the  construction  of  ])assenger 
cars  for  electric  railways  than  in  steam  coach  construction,  'i'he 
electric  car  must  have  low  steps  and  platforms  and  turn  short  curves. 


ELECTRIC    RAILWAYS 


Tlie  (littifulties  are  largely  in  tlie  floor  framing  of  tlie  car.  The 
platforms  at  each  end  are  usually  eight  to  ten  inches  lower  than 
the  floor  of  the  interior.  As  the  car  must  frequently  be  designed  to 
pass  around  curves  of  small  radius,  often  of  only  thirty  or  forty  feet, 
sufHcient  clearance  nnist  he  ])r()vi(led  for  the  swing  of  the  trucks. 
This  necessitates  that  the  trucks  of  a  douhle  truck  car  he  .set  far 
enough  hack  towards  the  center  of  the  car  to  clear  tlu'  dropped 
])latform  timbers,  .shown  in  Fig.  ()3.  In  the  illustration  .shown.  Fig. 
(■>],  the  truck  centers  are  but  21  feet  S  inches  a])art,  while  the  ends 
overhang  the  truck  centers  11  feet  4i  inches.  It  is  difhcult  to  suj>port 
this  overhanging  weight  properly.  The  difficulty  is  increa.sed  by 
the  fact  that  the  rear  platform  is  often  crowded  with  pa.s.sengers 
having  an  aggregate  weight  of  one  ton  oi-  uKjre.     Trusses  manifestly 


^rioor 


f   a       S 

"-S'xf  Steel  Place 


■^1  "tf  1^ 


Fi^C.  (>:).    RfiufoiviiiL,'  Plates. 


cannot  be  employed  to  give  rigidity  to  the  long  platform.  This  is 
usually  given  in  cars  of  wood  construction  l)y  reinforcing  the  plat- 
form timbers  with  steel  plates  as  shown  in  the  figure.  In  order  that 
the  dropping  tendency  of  the  j^latfonn  shall  not  bow  up  the  body 
of  the  car  between  the  trucks  this  portion  must  be  braced  rigidly, 
i'he  space  below  the  windows  and  above  the  side  sill  is  iitili/.ed  for 
this  purpo.se.  The  .side  sill  is  moreover  .strengthened  1)V  having  .steel 
plates  bolted  to  it. 

The  longitudinal  members  of  the  body  framing  are  termed 
sills.  These  are  iLsually  of  long  leaf  yellow  ])ine.  A  arious  com- 
binations of  wood  and  .steel  are  employed  for  sills,  an  example  of 
which  is  .seen  in  Figs.  (>1  and  ()2.  The  sills  are  kept  the  ])roper 
distance  apart  by  "bridgings"  or  cro.ss  sills  mortised  into  them 
at  intervals  and  by  "end  sills."  The  whole  framing  is  tied  together 
by  the  rods  rumiing  parallel  to  the  V^ridging.  The.se  tie  rods  are 
often  ])rovidc(|  with  turn  buckles  for  tightening  when  occasion  mav 
recinirc. 


V 


ELECTKIC    RAILWAYS  71 

The  outer  sills  are  termed  side  sills;  those  nearest  the  center 
of  the  car,  the  center  sills  or  draft  timbers;  while  those  between  are 
called  intermediate  timbers. 

The  remaining  portion  of  the  car  is  constructed  much  after 
the  manner  of  a  steam  coach.  The  posts  between  the  windows  are 
mortised  into  the  side  sill  at  the  bottom  and  into  a  top  sill  at  their 
upper  end.  They  arc  laterally  braced  by  a  belt  rail  immediately 
under  the  window  opening,  both  the  belt  rail  and  the  posts  being 
gained  out  so  that  the  rail  fits  flush  with  the  posts.  A  wide  letter 
board  gained  into  the  post  just  below  the  side  plate  adds  to  the  bra- 
cing of  the  side  of  the  car,  as  does  also  an  iron  truss  usually  one-fourth 
to  one-half  inch  thick  and  two  to  three  inches  wide  which  is  gained 
into  the  posts  on  the  inside  running  just  under  the  windows  between 
the  truck  centers,  and  then  descends  to  pass  through  the  side  sills 
and  fasten  by  a  bolt  underneath. 

The  roof  consists  of  the  upper  and  lower  decks.  That  portion 
over  tlie  platform  or  vestibule  is  termed  the  hood.  Rigidity  is  given 
to  the  whole  upper  j)ortion  of  the  car  by  the  end  ])lates  resting  on  the 
corner  posts  and  extending  between  the  side  plates  at  either  end  of 
the  car  body  proper,  and  by  steel  carlins  which  conform  to  the  pecuHar 
shape  of  the  roof  and  extend  between  the  side  plates.  I'he  steel 
carlins  are  usually  placed  over  alternate  side  posts.  Bolted  on  either 
side  of  them  and  ])laced  at  intervals  of  about  twelve  inches  between 
are  wood  carlins.  The  wood  carlins  of  the  lower  deck  extend  ffom 
the  side  plate,  to  which  they  are  fastened  by  screws,  to  the  top  sill, 
which  is  immediately  below  the  windows  of  the  upper  deck.  Above 
these  windows  is  the  top  plate,  supporting  the  carlins  of  the  upper 
deck,  which  extend  between  and  a  few  inches  beyond  the  two  top 
plates.  Poplar  sheathing  three-eighths  or  one-half  inch  is  nailed 
over  carlins  and  on  this  heavy  canvas  usually  of  six  or  eight  ounce 
duck  is  stretched  tiglxtly.  Several  coats  of  heavy  paint  on  the  canvas 
and  a  trolley  board  for  supporting  the  trolley  stand  complete  the 
roof.  On  the  underside  of  die  carlins  the  headlining,  usually  of 
birch  or  birdseye  maple,  is  .secured.  '^Fhis  forms  the  interior  finish 
of  the  ceiling  of  the  car. 

Steel  Car  Framing.  As  a  result  of  the  demands  of  the 
oflicials  of  the  New  York  Subwav  for  cars  of  greater  strength  and  less 


72  ELECTRIC    RAILWAYS 


sul)ject  to  danger  from  fire,  much  ])r()gress  has  been  made  in  the  last 
few  years  in  the  construction  of  cars  with  steel  framing.  Steel  con- 
struction is  much  more  expensive  than  that  in  which  the  framing  is 
of  wood  and  is  considerably  heavier.  The  advantages  lie  partly  in 
the  fact  that  it  is  more  durable,  but  the  great  reason  for  the  interest 
w  ith  which  the  new  style  of  construction  has  been  received  is  that  the 
danger  of  collapse  and  consecpient  injury  to  ])assengers,  in  case  of 
accident,  is  greatly  diminished. 

Car  Weights.  The  total  weight  of  a  .street  car  with  a  body 
1()  feet  long  over  corner  ])o.sts  mounted  on  a  single  truck  with  two 
motors  is  ap])roxiniately  14,000  pounds.  Of  this  the  body  weighs 
about  4,000  pounds,  the  truck  4,400  pounds,  and  the  inotors  and  the 
electrical  e([ui])ment  the  remaining  5,100  pounds.  The  weights  of 
the  separate  parts  of  a  certain  interurban  car  measuring  52  feet  6 
inches  over  the  bumpers  mounted  on  double  trucks,  one  of  which 
carried  two  motors,  is  body  34,005,  motor  truck  9,565,  ti'ail  truck 
6.670,  electrical  equipment  12,S00;  total  63,100. 

An  interurban  car  of  about  the  same  size  as  the  one  just  men- 
tioned but  e(|ui})ped  with  four  motors  gave  the  following  weights: 
Body  with  controller  and  i-esistance  grids  3!),()()()  pounds,  trucks 
19,130  ])ounds,  motors  15,420  poiuids;  total  73,550  pounds. 

Car  Painting.  A  great  deal  of  attention  is  given  to  the  proper 
painting  of  cars.  A  car  ])ainted  with  care  and  proper  materials 
always  presents  an  attractive  ap{)earan(e,  while  one  carelessly  j)ainted 
is  reatlily  noticealjle.  New  cars  go  tlirougli  an  elaborate  painting 
process.  The  time  recjuired  is  from  two  to  three  weeks.  The  fol- 
lowing scheme  may  he  regarded  as  an  example  of  a  good  process: 

A  coat  of  primer  is  given  the  car  tlie  lirst  day.  Ou  the  thinl  clay  all 
irrej^ularities  are  puttied  up  smooth.  Ou  the  fourth  and  fifth  days  a 
heavy  primer  is  applied,  one  coat  ou  each  day.  A  coat  of  tiller  is  gi\eu 
ou  the  sixth  day  and  allowed  to  harden  the  following  day.  The  next  paint 
applied  is  termed  a  guide  coat.  This  is  of  a  color  diflereut  froui  the  pre- 
ceding ones  and  serves  as  a  guide  for  tlie  rubbers,  wlio  on  the  following 
day  go  over  the  ear  with  mineral  wool,  line  saudpaj)er,  or  pumice  stoue 
and  rub  it  until  the  guide  coat  is  worn  away.  This  assures  an  even  and 
smooth  surface.  Ou  the  tenth  day  the  car  is  allowed  to  staiul.  A  coat  of 
the  color  desired  is  aiiplied,  one  on  each  of  the  following  tiiree  (htys.  Ou 
the  f<nuteeuth  and  lifteentii  days  tlie  car  is  striped  witli  tlie  desired  orna- 
ments and  lettered.  This  is  usually  done  in  aluniinuni  or  gold  leaf.  The 
car  is  then  gi\  en  tliree  coats  of  varnish  on  alternate  days,  and  the  work  is 
com|)leted.  The  best  practice  brings  the  cars  in  once  each  year  to  be 
revarnisheil. 


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ELECTRIC  RAILWAYS, 


OVERHEAD  CONSTRUCTION. 

•  Trolley  Wire.     T^he  trolley  wire  is  suspended  from  the  span 
wires  or  brackets  in  such  a  way  as  to  permit  of  an  uninterrupted 
passage  of  an  upward  pressing  trolley  wheel  underneath  it.    The 
trolley  wire  itself  may  be  either  round,  grooved,  or  figure  8  in  section. 
Where  a  round  v/ire  is  used.  No.  00  B.  &  S.  gauge  is  the 
most  common  size.     Figure  8  wire,  so  called  from  its  sec- 
tion, which  is  shown  in  Fig.  04,  is  designed  to  present  a 
smooth  under  surface  to  the  trolley  wheel,  wliich  will  not 
be  interrupted  by  the  clamps  or  ears  used  to  support  it. 
Clamps  are  fastened  to  the  upper  part  of  the  figin-e  S. 
I^'lie  grooved  wire  is  rolled  with  grooves  into  which  the    pjir.  04. 
supporting   clamps    fasten.     This    wire    also   presents   a 
smooth  imder  surface  to  the  trolley  wheel. 

Trolley=Wire   Clamps   and    Ears.     The  trolley   is   supported 
either  by  clamps  or  by  soldered  ears.     One  type  of  clamp  grasps  the 


Fig.  65.    Trolley  Wire  Clamp  and  Ear. 

wire  by  virtue  of  .screw  pres.sure.  A  soldered  oar  is  .shown  at 
E,  Figo  Go.  This  ear  has  small  projections  at  each  end,  which 
are  bent  around  the  wire  to  assist  the  solder  in  holding  the  wire 
to  the  ear.  Another  form  of  ear,  u.sed  to  some  extent,  holds  the 
wire  bv  virtue  of  havine;  the  edi2;es  of  the  ";roove  off.set  or  riveted 
around  the  wire. 


74 


ELECTRIC    RAILWAYS 


Tlie  ear  or  damp  screws  to  a  l)olt  which  is  insulated  from  the 
metal  ear  through  which  passes  the  span  wire.  A  cross-section 
through  a  connnon  ty])e  of  trolley-wire  hanger  is  shown  in  Fig.  (iO. 
Here  there  is  an  ontei'  shell  of  metal,  which  is  adapted  to  hook  to 
the  span  wire.  In  this  .shell  is  an  insulating  bolt,  that  is,  a  holt 
svuTounded  with  some  form  of  insulating  material  which  is  very 
strong  mechanically  and  not  likely  to  l)e  cracked  by  the  hammering 
action  of  the  pa.ssing  trolley  wheel.  Most  of  the  in.sulating  coni- 
])oun(ls  used  in  making  trolley-wire  insulators  ai-c  trade  secrets. 
Another  kind  of  insulator  called  the  "cup  and  cone"  type  is  shown 


Fig.  W.    ( 'ross-Sectiou  Ti-olley  Wire  Haugt-r. 

at  C,  Fig.  ()")o  In  these  insulators,  the  metal  part  B  which  fa.stens 
to  the  .span  wire  does  not  completely  surround  the  insulation  C. 
Wood  has  sometimes  been  used  for  the  insulation  of  trolley-wire 
hangers. 

Span  Wires.  In  city  streets,  the  trolley  wire  is  commonly 
su.spended  from  span  wires  stretched  between  poles  locatetl  on 
both  sides  of  the  .street.  These  span  wires  are  of  j-inch  or  i^-inch 
galvanized  stranded  steel  cable.  In  order  to  add  to  the  insulation 
between  the  tiolley  wire  and  the  poles  at  the  side  of  the  street,  what 
is  called  a  fttrain  insulator  is  placed  in  the  s])an  wire.  '^Fhis  is  an 
insulator  adaj)ted  to  witlistand  the  great  tension  put  upon  it  by  the 


ELECTiUC    KAlLWxVVS 


75 


span  wire.  One  (^f  tliese  is  shown  in  Fig.  ()7.  Means  are  usually 
pi-(jvi(le<l  for  tightening  the  span  wires  as  they  stretch  and  as  the 
poles  give  under  the  strain.  The  insulator  in  Fig.  67  has  a  screw 
eye  for  that  ])urpose. 


Pi^;.  (57.     Strain  Insulator. 


Brackets.  In  the  bracket  type  of  overhead  construction,  a 
trolley  wire  is  fastened  to  brackets  placed  on  poles  near  the  track. 
This  construction  is  used  on  suburban  and  interurban  lines  where 
the  presence  of  poles  near  the 
track  is  not  objectionable. 
It  has  been  found  that  a  rigid 
connection  of  the  trolley  wire 
to  a  bracket  is  likely  to  result 
in  the  breaking  of  the  trolley- 
wire  insu-lators.  For  this 
reason  the  l)rackets  now  com- 
monly used  provide  for  a  flex- 
ible suspension  of  the  trolley- 
wire  hanger  from  the  bracket. 
A  bracket  employing  such 
flexible  construction,  made 
by  the  Ohio  Brass  Company, 
is  illustrated  in  Fig.  OS. 

An  example  of  standard 
straight-line  bracket  con- 
struction is  showni  in  Fio;.  09. 

Feeders.  Where  addi- 
tional conductivity  is  needed 
beyond  that  furnished  bv  the 

.        .  "  Fig.  68.    Overhead  Construction. 

trolley  wire  itself,  feeders  are 

run  on  insulators  along  the  poles   at  the  side  of  the  track.     Such 

feeders  are  connected  to  the  trolley  wire  at  regular  intervals.     Where 


lb 


ELECTRIC    KAILWAYS 


span-wire  constriK-tion  is  used,  the  feed  wire  may  he  suhstituted  for 
the  span  wire  at  the  pole  where  the  connection  hetween  feed  wire 
and  trolley  wire  is  made.  In  such  a  <;isr,  of  course,  a  trolley-wire 
hanger  is  used  which  .has  no  insulator,  so  that  the    current    feeds 


Cr/K 


e'eplnZi 


Note  ..I 

Coins  to  be  ^ 
devp  ^o'poies 
Hake  B" 


Fig.  69.    Standard  Straight  Line  Construction. 

directly  through  the  hanger.     Another  method  is  to  nm  the  feed  con- 
nection parallel  with  a  span  wire  and  a  short  distance  from  it. 

Section  Insulators.  Section  insulators  are  usually  placed  in 
the  trolley  wire  at  regular  interyals.  Such  a  section  insulator  is 
shown  in  Fig.  70.     Its  jnirpose  is  to  insulate  one  section  of  trolley 


ELECTRIC    RAILWAYS 


77 


wire  from  tlie  iioxt,  so  tliat  in  case  tlie  trolley  wire  of  one  section 
breaks,  or  is  ifroniided  in  anv  other  maimer,  that  section  can  be  dis- 
connected  an<l  llic  other  sections  on  cither  side  ke])t  in  oj)eration. 
In  hirge  city  street-railway  systems,  each  section  of  trolley  wire  nsnally 
has  its  own  feeder  or  feeders,  independent  of  the  other  sections. 
This  feeder  is  supphed  through  an  automatic  circuit  breaker  at  the 
power  house.  In  case  a  certain  section  of  trolley  wire  is  groimded 
the  large  current  that  immediately  flows  will  open  the  circuit  breaker 
supplying  that  section;  but,  unless  the  ground  contact  is  of  an  ex- 
tremely low  resistance,  it  will  not  affect  the  operation  of  the  other 
feeders.     Should  it  be  of  sufficiently  low  resistance  to  cause  all  the 


Fin'.  TO.     Section  Insulator. 


generator  circuit  breakers  to  open,  it  would,  of  course,  interrupt  the 
entire  service  temporarily;  but  usually  the  circuit  ])reaker  on  any 
individual  feeder  will  cut  that  feeder  out  before  all  the  circuit  breakers 
will  open. 

High=Tension  Lines.  Where  high-tension  alternating-current 
wires  are  run,  as  in  the  case  where  thef  road  is  of  such  length  as  to 
recjuire  the  establishment  of  several  substations,  the.se  high-tension 
circuits  are  usually  carried  some  distance  above  the  500-volt  direct- 
current  trolley  and  feeders.  An  example  of  interurban  overhead 
con.struction  is  shown  in  Fig.  69.  Here  the  high-tension  wires  are 
carried  on  large  porcelain  insulators  of  a  size  necessary  for  20,000 
volts.  These  insulators  are  placed  35  inches  apart.  High-tension 
wires  are  kept  so  far  apart  because  of  the  danger  that  arcs  will  in 
some  way  be  started  between  the  lines,  as  the  high-tension  current 
will  maintain  an  extremely  long  arc.  The  blowing  of  green  twigs 
across  the  lines,  or  birds  of  sufficient  size  flying  into  the  lines,  is  likely 
to  establish  arcs  which  will  temporarily  short-circuit  the  line.     The 


78  ELECTRIC    RAILWAYS 


tjrejitor   the  tlislaiici'    ;ii)iiii   of   llic   wires.   (In-    k-ss  daiig-ei'  tliat   such 
tliiiiti's  will  (icciir. 

Botli  j^lass  and  porcelain  insulators  are  successfully  used  on 
lines  of  verv  liiji'li  tension.  ( dass  is  the  chea])er  and  porcelain 
has  the  p-eater  ineclumical  strength. 

Ilif^h-teiision  wires,  are  usually  of  hard-<lrawn  copjier  or  of 
aluniinuni  made  up  in  the  form  of  a  cai)le  of  several  strands.  Alu- 
niinmn  is  litjjhter  for  a  given  conductivity  than  copper;  and,  at  the 
market  price  controllin*;;  at  the  present  time,  is  chea])er.  It  is,  how- 
ever, more  subject  to  nnevenness  of  com])osition,  which  leaves  weak 
spots  at  certain  points  in  the  wire;  and  that  is  the  reason  why  alu- 
minum is  now  always  nsed  in  the  form  of  a  stranded  cable  rather 
than  as  a  sin<2,le  conductor.  Aluminum,  being  considerably  softer 
than  copper  and  nuOting  at  a  lower  temperature,  is  more  likely  to 
be  worn  tln-ough  as  a  result  of  abrasions  or  to  be  melted  off  by  a 
temporary  arc.  These  slight  objections  are  ))alance(l  against  its 
.smaller  first  cost  as  com])ared  with  the  cost  of  cojiper. 

The  calculation  of  the  proper  amount  of  feetl  wire  for  a  given 
.section  of  road  is  .somewhat  similar  to  the  calculation  t)f  electric 
light  and  power  wiring  as  already  ovitlined.  It  is  fir.st  necessary  to 
estimate  approximately  the  amount  of  current  recjuire.d  at  different 
portions  of  the  line.  The  amonnt  of  drop  to  be  allowed  between 
the  ])ower  hou.se  and  cars  must  be  decided  arbitrarily  by  die  engineer. 
A  dro])  of  10  per  cent  is  j)robably  the  one  nio.st  commonly  figured 
upon  in  designing  feeding  .systems.  The  resistance  in  ohms  of  the 
copper  feeders  recpiired  to  conduct  a  given  current  with  a  given  loss 
in  volts,  can  be  calculated  by  dividing  the  volts  lost  by  die  current, 
according  to  Ohm's  law.  By  the  aid  of  a  table  which  gives  die 
conductivity  of  various  sizes  of  wire  according  to  the  methods  out- 
lined in  connection  widi  "Electric  Wiring,"  the  ])roper  mnnber  and 
.size  of  the  feeders  can  be  determined.  The  most  difficult  thing  to 
determine  is  the  load  that  will  be  j)laced  upon  any  .section  of  the  line. 
Of  course,  there  will  be  times  when  cars  are  bunched  together  owing 
to  blockades.  It  is  out  of  the  question  to  provide  enough  feeder 
copper  to  keep  the  lo.ss  in  voltage  within  rea.sonable  limits  at  .such 
times.  The  ordinary  load  upon  any  feeder  is  used  as  the  basis  of 
calculation  in  most  cases.     The  amount  of  current  recpiired  per  car 


ELECTKIC    ]{AILWAYS 


79 


depends  on  the  weight  of  the  car  and  the  character  of  the  service, 
"^rhis  will  be  taken  up  later  under  the  head  of  "Operation." 


Location. 


THIRD    RAIL. 

The    third-rail     jvstem 


of    coniluctinir    current    to 


Fig.  71.     Thira-Ruil  Insulntor. 


electric   cars,   as  most   commonly   employed    in   the   T'nited    States, 
follows  the  example  set  by  the  IMetropolitan  West  Side  Elevated 
Uailwav  of  (liicago.     All  the  ele- 
vated    road.s   in    the    United    States 
are  now  operated  by  means  of  third 
rails    located    at    one    side    of  the 
track.     The  third  rail  is  an  ordinary 
T-rail  and  is  located  with  the  center 
of  its  head  20  inches  outside  of  the 
gauge  line  of  the  nearest  track  rail, 
and  6j'\.^    inches    above    the  top  of 
the  track  rail.     On  a  few  interurban 
roads    this    di.stance    has   been   in- 
creased in  order  to  accommodate  certain  steam  railroad  rolling  stock 
which  must  at  times  be  operated  over  the  line. 

Insulators.  The  third  rail  is  supported  every  fifth  tie  on  an 
insulator.  These  insulators  on  first  construction  were  made  of 
wooden  blocks  ])oiled  in  paraffine,  but  at  the  present  time  more 
substantial  forms  of  insulation  are  being  used. 

One  form  of  third-rail  insulator,  known  as  the  "  Gonzenbach," 
has  a  ba.se  of  cast  iron  resting  on  the  tie.  Over  this  is  placed  a  cap 
of  insulating  material  similar  to  that  used  in  strain  and  trollev-wire 
insulators.  Over  this  insulating  material  is  another  cast-iron  cap 
upon  which  the  third  rail  rests.  Tlie  weight  of  the  third  rail  holds 
it  in  position,  and  there  is  no  clamping  together  of  the  various  parts 
of  the  insulator. 

Another  form  of  third-rail  insulator  is  made  of  what  is  .called 
"reconstructed  granite,"  and  another  of  vitrified  clay.  Fig.  71 
shows  one  of  the  latter. 

Switches.  Where  the  third  rail  is  used,  a  contact  shoe  is 
placed  on  each  side  of  both  trucks  of  the  motor  car.  At  switches 
it  is  necessary  to  omit  the  third  rail  for  a  short  distance  <m  one  side 


80  ELECTRIC    RAILWAYS 


of  the  track,  and  place  a  sliorl  si'ctioii  of  (liiid  lail  on  llic  otlicr  side 
of  the  track  so  tliat  the  current  .suj)j)ly  to  the  car  will  he  uninterrupted. 

At  Highway  Crossings.  Where  the  third-rail  system  is  eni- 
])l()ved  on  interurl)an  surface  lines,  it  is  necessary  to  omit  a  section 
of  it  at  every  highway  crossing.  If  the  crossing  is  too  wide  to  be 
bridged  across  by  a  car,  the  car  must  have  sufficient  momentum  to 
(h-ift  over  such  crossings  wlien  it  comes  to  them.  To  connect  across 
the  break  in  the  third  lail  at  such  points,  an  undergrotmd  cable 
is  generally  used.  This  cable  must  be  thoroughly  protectetl  against 
leakage  of  moisture  into  the  insulation  where  it  comes  to  the  surface 
for  connection  to  the  third  rail. 

Another  form  of  third  rail,  laid  several  years  ago  on  some  of 
the  lines  of  the  New  York,  New  Haven  »S;  Hartford  Railroad,  was 
of  an  inverted  V-shape,  and  was  laid  midway  between  the  track 
rails  with  its  top  1  inch  above  them  and  its  bottom  only  If  inches 
above  the  ties.  It  was  suj)ported  on  wooden  blocks.  This  location 
of  the  third  rail  has  never  been  popular,  because  of  the  poor  insula- 
tion with  the  rail  located  so  close  to  the  ties  between  the  rails. 

Conductivity.  The  conductivity  of  a  steel  rail  varies  consid- 
erably. A  rail  of  the  ordinary  composition  used  on  .steam  railroads 
is  too  high  in  carbon  to  give  the  best  conductivity.  Such  a  rail 
has  al)out  one-tenth  the  conductivitv  of  the  same  cross-.section  of 
copper.  Steel  can  easily  be  obtained,  however,  which  will  have 
one-seventh  the  conductivity  of  copper,  and  the  additional  co.st  of 
obtaining  such  special  steel  is  cjuite  low,  so  that  the  majority  of 
roads  installing  the  third-rail  system  have  seen  fit  to  pay  the  extra 
cost  and  thereby  sectu'e  a  softer  rail  than  that  usually  emploved  in 
track  rails. 

Cost.  The  co.st  of  the  third-rail  system  is  less  than  an  over- 
head trolley  system,  provided  enough  copper  is  placed  in  the  trolley 
feeders  to  make  the  conductivity  of  the  trolley  system  equal  to  that 
of  the  third-rail  system.  It  is  very  seldom,  however,  that  a  trolley 
svstem  is  so  constructed  on  an  interurban  road;  and  hence  the  trollev 
.system,  as  usually  constructed,  is  cheaper  than  the  third-rail  .system, 
because  it  is  not  of  equal  conductivity  to  a  third-rail  system. 

Advantages  in  Operation.  Where  verv  heaw  cars  or  trains 
Are  to  be  operated,  the  third-rail  system  is  decidedly  an  advantage, 
for  two  rea.sons      Iii  me  first  ])lace,  it  affords  the  cheaper  method 


ELECTRIC    RAILWAYS 


81 


of  conducting  a  fjjivcn  licavv  volume  of  ciUTcnt;  and  in  the  second 
place,  the  contact  shoes  that  conduct  the  current  from  the  third  rail 
to  the  movinnj  car  or  train  are  built  to  carry  a  much  larger  volume 
of  current  than  the  trolley  wheel,  which  has  only  a  small  area  of 
contact  on  the  troUev  wire.  Ordinarily  there  are  two  of  these  contact 
shoes  in  multiple  for  every  motor  car. 

Another  atlvantage  of  the  third  rail  over  the  trolley  is  that  the 
trolley  may  leave  the  wire  at  high  speeds  or  in  passing  switches. 
On  well-constructed  roads,  where  the  trolley  wire  is  kept  in  good 
alignment  and  the  track  is  smooth,  there  is  little  trouble  from  this 


Vi^^.  7-1.    Cross-Section  of  Conduit. 


.source;  l)ut  it  is  undoubtedly  a  convenience  to  be  able  to  operate 
cars  or  trains  without  giving  any  attention  to  a  trolley  pole. 

CONDUIT    SYSTEMS. 

The  vmdertjround  conduit  sv.stem,  in  which  the  conductors 
conveying  the  current  to  the  cars  are  located  in  a  conduit  under 
the  tracks,  is  in  use  in  two  cities  of  the  United  States — New  York 
City  and  Washington,  1).  C.  The  cost  of  this  system,  and  the 
danger  of  interruption  of  the  service  where  the  drainage  is  not  excel- 
lent, have  prevented  its  more  extensive  adoption. 

The  New  York  type  of  conduit  is  a  good  example  of  this  con- 
struction. The  conductors  con.sist  of  T-bars  (CC)  of  .steel  supported 
from  porcelain  cup  insulators  located  15  feet  apart  in  the  conduit. 
A  cross-section  of  the  conduit  is  shown  in  Fig.  72.  At  each  insulator 
a  handhole  is  provided  (Fig.  73),  so  that  access  may  be  had  to  the 
insulator  from  the  street  surface.     Manholes  are  provided  at  intervals 


82 


ELECTKTC    KATLWAYS 


of  about  150  feet,  so  that  the  dirt  which  collects  in  the  conduit  can 
be  scraped  into  these  manholes  and  removed  at  intervals.  The 
manholes  also  serve  as  points  of  drainafje  to  the  sewer  system. 

Contact  Plow.  Current  is  conducted  to  the  car  throu<i;h  a 
pair  of  contact  shoes  commonly  called  a  plov  (Fig.  74).  This  ])lo\v 
has  the  two  shoes  insulated  from  each  other,  and  from  the  frame 
of  the  ])low.  They  arc  ju-ovided  with  flat  sprino;s  that  hold  the 
shoes  apiinst  the  conductin<j:  bars  in  the  conduit.  The  .shank  of 
the  plow  is  thin  enough  (,''g  inch)  to  enter  the  .slot  of  the  conduit. 

The  conductors  pass  up  through 
the  middle.  These  plows  can, 
of  cour.se,  be  removed  only  when 
the  car  is  over  an  open  pit. 

Cost.  A  conduit  .system  of 
this  kind  is  very  expensive  to 
build  because  of  the  fact  that  a 
very  deep  excavation  must  be 
made  in  the  .street  to  accommo- 
date the  conduit.  The  track 
rails,  slot  rails,  and  .sheet-steel 
conduit  lining  are  held  in  align- 
ment by  cast-iron  yokes  placed  5 
feet  apart.  The  entire  space 
around  and  underneath  these 
yokes  is  filled  with  concrete  in 
order  to  give  rigidity  and  a  per- 
uuinent  track.  Three  expensive 
Items,  therefore,  cuter  into  the  construction  of  a  conduit  road — 
namely,  the  deep  excavation,  which  may  call  for  the  changing  of 
other  imderground  ])ipes  or  conduits  in  the  street;  the  large  amount 
of  iron  and  .steel  needed  for  the  .yokes  and  slot  rails;  and  the  large 
amoinit  of  concrete  needed. 

On  American  conduit  roads  the  slot  and  conduit  are  placed 
under  the  middle  of  the  track.  Some  of  these  roads  are  simply 
recon.structed  cable-conduit  roads  in  which  the  old  cable  conduit 
has  been  u.sed  for  electrical  conductors.  In  the  conduit  road  at 
Buda-Pest,  Hungary,  the  slot  is  placed  alongside  one  of  the  track  rails. 


Kill.  T:i.     HaiuUiolo, 


ELECTRIC    RAILWAYS 


83 


Current  Leakage.  The  leakage  on  an  underground  conduit 
road  is  considerable,  because  the  insulators  are  necessarily  located 
in  a  dani]),  -dirty  ])lace,  which  causes  leakage  over  the  surface  of 
the  insulators.  This  leakage,  however,  is  not  prohibitive  so  long 
as  the  conductor  rails  are  not  under  water.  If  on  account  of  poor 
drainage  the  conductor  rails  become  submerged,  the  leakage  becomes 
so  great  that  it  is  im- 
possible to  operate 
the  road. 

It  will  l)e  noticed 
that  the  conduit  sys- 
tem as  illustrated 
here  employs  two 
conductor  rails — one 
for  the  positive  side 
of  the  circuit  and  the 
other  for  the  negative. 
The  track  rails,  there- 
fore, are  not  used  as 
conductors,  and  one 
sitle  of  the  circuit  is 
not  grounded  as  in 
the  ordinary  trolley 
system,  although  the 
leakage  to  ground 
may  be  considerable 
from  one  or  both  con- 

ductor  rails. 

TRACK  CONSTRUCTION. 

Girder  Rail.  A  great  variety  of  track  rails  are  used  in  electric 
railways.  The  most  common  at  one  time  was  the  girder,  a  typical 
section  of  which,  with  joint,  is  illustrated  in  Fig.  75.  This  is  an 
outgrowth  of  the  old  tram  rail  used  on  horse  railways.  It  has  a 
tram  alongside  of  the  head,  on  which  vehicles  may  be  driven.  Its 
chief  advantage  from  the  standpoint  of  the  railway  company  is  that 
there  is  plenty  of  room  for  dirt  and  snow  to  be  pushed  away  by  the 
flanges  of  the  cars.  If  the  company  maintains  the  paving,  it  may 
be  to  its  advantage  to  have  teams  use  the  steel  track  rather. than  the 


Fig.  T4.     Contact  Plow. 


84 


ELECTKIC    E  AIL  WAYS 


paving,  although  tliis  advantage  in  maintenance  is  pr()l)al)ly  more 
than  compensated  for  l.y  the  dehiy  of  ears  through  the  regular  use 
of  the  track  hy  teams. 

Trilby  Qroo>e  Rail.  A  uioditication  of 
the  girder  rail,  known  as  the  Trilhi/,  and  some- 
times a,s  the  grooved  girder,  is  shown  in  Fig.  7(). 
A  rail  similar  tt)  this  is  used  in  several  large 
cities  of  the  United  States.  It  has  a  groove 
of  such  a  shape  that  the  Hanges  of  the  car 
wheels  will  force  snow  and  dirt  out  of  it  instead 
of  packing  it  into  the  bottom  of  the  groove,  as 
in  the  case  of  the  regular  European  narrow- 
grooved  rail.  A  narrow-grooved  rail  in  which 
the  grooves  correspond  closely  to  the  sha})e  of 
the  car-wheel  flanges  is  sure  to  make  trouble 

in  localities  where  there  is  snow  and  ice,  as  the  grooves  become 
packed  and  derail  the  cars. 

Shanghai  T=Rail.     Tn  some  systems 
:§|:Lzr;."7:$|  a  T-rail  is  used.     Where  the  T-rail  is 

to  be  used    with   ])aving,  the   popular 

form  is  the  Shanghai  T,  .shown  in  Fig. 

77.     This  rail  is  high  enough  to  ])ennit 

the  use  of  high  jKiving  blocks  around  it. 


I-'iK-  "?•■    Girder  Rail. 


Sireet  Ry. Journal 

Fig.  76.    Grooved  Kail. 


^^  Strctl  Ky.Juurual 

Fin.  77     Shanghai  T-Rail  aud  Joiut. 


Common  T=Rail.     The  I'-rail  u.sed  by  steam  railroads  is  known 
as  the  A.  S.  ('.  K.  .standard  T-rail,  because  it  follows  the  standard 


ELECTRIC    RAILWAYS 


85 


dimensions  recommended  for  T-rails  by  the  American  Society  of 
Civil  Engineers.  A  standartl  Go-pound  T-rail  of  this  kind  is  shown 
in  Fig.  78.  Other  weights  of  this  rail  have  the  same  relative  pro- 
portions. Such  a  rail  is  used  for  interurban  roads,  and  for  suburban 
lines  in  streets  where  there  is  no  block  paving.  The  high  rails  are 
used  to  facilitnte  paving  with  high  paving  blocks. 

Track  Support.  The  greater  portion  of  track  is  laid  on 
wooden  ties.  These  ties,  in  the  most  substantial  wooden  tie  con- 
struction, are  G  inches  bv  8  inches  in  section,  and  8  feet  lono;.  Thev 
are  spaced  two  feet  between  centers.  Sometimes  smaller  ties,  spaced 
farther  apart,  are  used  in  cheaper  forms  of  construction;  but  the 
foregoing  figures  are  those  of  the  best  con- 
struction known  in  American  railway  practice. 
In  paved  streets,  ties  are  usually  employed, 
although  sometimes  what  is  known  as  "con- 
crete stringer"  construction  is  used  instead  of. 
ties  to  support  the  rails.  A  strip  of  concrete 
about  12  inches  deep  is  laid  under  each  rail, 
and  the  rails  are  held  to  gauge  by  ties  or  tie 
rods  placed  at  frequent  intervals.  Sometimes 
the  concrete  is  made  a  continuous  bed  under 
the  entire  track.  In  most  large  cities  the  con- 
crete foundation  is  used  under  all  paving;  and  consecjuently,  when 
concrete  is  used  instead  of  ties  to  support  the  rails,  this  concrete  is 
simply  a  continuation  of  the  paving  foundation.  Where  ties  are  used, 
they  are  laid  sometimes  in  gravel,  crushed  stone,  or  sand,  although 
frequently,  in  the  largest  cities,  they  are  embedded  in  concrete. 
Sometimes  this  concrete  is  extended  under  the  ties,  and  sometimes 
it  is  simply  put  around  the  ties. 

Ballast.  A  ballast  of  gravel,  broken  stone,  cinders,  or  other 
material  which  is  self  draining  and  which  will  pack  to  form  a  solid 
bed  under  the  ties,  should  be  used  to  get  the  best  results  under  all 
forms  of  tie  construction,  wiiether  in  pavetl  streets  or  on  a  [)rivate 
right  of  way,  as  pn  an  interurban  road.  Of  course,  if  concrete  is 
placed  under  the  ties,  the  gravel  or  rock  ballast  is  not  necessary. 
If  ties  are  placed  directly  in  soft  earth,  which  forms  nnid  when 
wet,  they  will  work  up  and  down  under  the  weight  of  passing  trains, 
and  an  insecure  foundation   For  the  track  will  i)e  the  result. 


t  Ry.JuurL;i) 


Fig.  78.    StiiiKliinl  .V..S. 

C.  E.  Kuil  iind  Que 

Joint  Platf. 


86  ELECTRIC    RAILWAYS 

Joints.  The  matter  of  securing  a  proper  joint  for  fastening 
together  the  ends  of  rails  so  as  to  make  a  smooth  riding  track  without 
appreciable  jar  or  jolt  when  the  wheels  pass  a  joint,  has  iieen  given 
much  study  hv  electric  railway  engineers.  A  section  through  an 
ordinary  bolted  angle-V)ar  joint  is  shown  in  Fig.  75.  This  joint  is 
formed  by  bolting  a  couple  of  bars,  one  on  each  side  of  the  rails. 
The  edges  of  these  bars  are  made  accurately  to  such  an  angle  that 
they  will  wedge  in  between  the  head  and  base  of  the  rail  as  the  bolts 
are  tightened;  hence  the  name  angle  bars.  This  is  the  form  of  joint 
generally  used  on  steam  railroads  and  on  electric  roads  in  exposed 
track,  or  in  track  where  the  joints  are  easily  accessible,  as  in  dirt 
streets.  In  paved  streets,  the  undesirability  of  tearing  up  the  pave- 
ment frecpiently  to  tighten  the  bolts  on  such  joints,  has  led  to  the 
invention  of  several  other  tvpes,  which  will  be  described  later.  Never- 
theless very  good  results  have  been  obtained  in  recent  years  with 
bolted  joints  laid  in  paved  streets  where  care  has  been  given  to  details 
in  laying  the  track,  and  where  the  joints  have  been  tightened  several 
times  before  the  paving  is  finally  laid  around  them. 

Welded  Joints.  Several  forms  of  welded  joints  are  in  use. 
All  these  welded  joints  fasten  the  ends  of  the  rails  together  so  that 
the  rail  is  practically  continuous— just  as  if  there  were  no  joints — 
so  far  as  the  running  surface  of  the  rail  is  concernetl.  It  was  thought 
at  one  time  that  a  continuous  rail  would  l)e  an  impossibility  because 
of  the  contraction  ami  expansion  of  the  rail  under  heat  and  cold, 
which,  it  was  thought,  would  tend  to  pull  the  rails  apart  in  cold 
weather  and  to  cause  them  to  bend  and  buckle  out  of  line  in  hot 
weather.  Experience  has  conclusively  shown,  however,  that  con- 
traction and  expansion  are  not  to  be  feared  when  the  track  is  laid 
in  a  street  where  it  is  covered  with  paving  material  or  dirt.  The 
paving  tends  to  hold  the  track  in  line,  and  to  protect  it  from  extremes 
of  heat  and  cold.  The  reason  that  contraction  and  expansion  do 
not  work  havoc  on  track  with  welded  joints,  is  probably  that  the 
rails  have  enough  elasticity  to  provide  for  the  contraction  and  expan- 
sion without  breaking. 

It  is  found  that  the  best  results  are  secured  by  welding  rail 
joints  during  cool  weather,  so  that  the  effect  of  contraction  in  the 
coldest  weather  will  be  niininuuu.  In  this  case,  of  course,  there 
will  be  consideral)le  expansion  of  the  track  in  the  hottest  weather, 


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UBRARY 

Of  THE 

jNIVERSffY  of  lUiN^' 


ELECTRIC    RAILWAYS 


87 


but  this  does  not  cause  serious  bending  of  the  rails;  whereas  occa- 
sionally, if  the  track  is  welded  in  very  hot  weather,  the  contraction 
in  winter  will  cause  the  joint  to  break. 

Cast=Welded  Joints.  The  process  of  cast-welding  joints  con- 
sists in  pouring  very  hot  cast  iron  into  a  mould  placed  around  the 
ends  of  the  rails.  These  moulds  are  of  iron;  and  to  prevent  their 
sticking  to  the  joint  when  it  is  cast,  they  are  painted  inside  with 
a  mixture  of  linseed  oil  and  graphite.  Iron  is  usually  poured  so 
hot  that,  before  it  cools,  the  base  of  the  rail  in  the  center  of  the  molten 
joint  becomes  partially  melted,  thus  causing  a  true  union  of  the  steel 
rail  and  cast-iron  joint.  This  makes  the  joint  solid  mechanically 
and  a  good  electrical  conductor.     To  supply  melted  cast  iron  during 


Fig.  79.    Process  of  Cast-Welding  Joint. 

the  process  of  cast-welding  joints  on  the  street,  a  small  portable 
cupola  on  wheels  is  employed.  Fig.  79  gives  an  idea  of  the  process 
of  making  cast-welded  joints. 

Electrically  Welded  Joints.  An  electrically  welded  joint  is 
made  l)y  welding  steel  blocks  to  the  rail  ends.  A  steel  block  is 
placed  on  each  side  of  the  joint,  and  current  of  very  large  volume 
is  passed  through  from  one  block  to  the  other.  This  current  is  so 
large  that  the  electrical  resistance  between  the  rail  and  steel  block 
causes  that  point  to  become  molten.  Current  is  then  shut  off,  and 
the  joint  allowed  to  cool.  There  is  in  this  case  a  true  wekl  between 
the  .steel  blocks  and  the  rails  and  joint. 


88  ELECTRIC    KAIL  WAYS 


An  electric  welding  outfit  i)eing  expensive  to  maintain  and 
operate,  this  process  is  used  only  where  a  large  anioinit  of  ^-elding 
can  be  done  at  once.  Current  is  taken  from  the  trolley  wire.  A 
rotarv  converter  set  takes  oOO-volt  direct  current  from  the  trolley 
wire,  and'  converts  it  into  alternating  current.  This  alternating 
current  is  taken  to  a  static  transformer  v.hich  reduces  the  voltage 
and  gives  a  current  of  great  (juantity  at  low  voltage,  the  latter  cur- 
rent being  passed  through  the  blocks  and  rails  in  the  welding  proc- 
ess. A  mas.sive  pair  of  clamps  is  used  to  hold  the  blocks  against 
the  rails,  and  to  conduct  the  current  to  and  from  the  joint  while 
it  is  being  welded.  These  clamps  are  water-cooled  by  having  water 
circulated  through  them  .so  that  they  will  not  become  overheated 
at  the  point  of  contact  with  the  steel  blocks. 

Thermit  Welding.  A  process  of  welding  rail  joints  which"* 
was  developed  after  the  cast-welding  and  electric-welding  processes, 
is  known  as  the  Goldschmidi  process,  which  makes  use  of  a  material 
called  "thermit"  for  supplying  heat  to  make  the  weld.  A  mould 
is  placed  around  the  joint  and  the  thermit  is  put  in  this  moukl  and 
ignited.  The  heat  produced  by  the  thermit  is  so  intense  as  to  reduce 
the  iron  in  the  thermit  mixture  and  make  a  welded  joint.  The 
thermit  consists  of  a  mixture  of  finely  powdered  aluminum  and  iron 
oxide.  ^Yhen  this  is  ignited,  the  aluminum  oxidizes,  that  is,  alxsorbs 
oxygen  so  rapidly  that  an  intense  heat  is  the  result.  In  the  process 
of  oxidation,  the  aluminum  takes  the  oxygen  from  the  oxide  of  iron, 
leaving  molten  metallic  iron,  which  metallic  iron  makes  the  weld 
by  union  w^ith  the  molten  rail  ends.  This  process  has  the  advantage 
over  other  welding  processes,  of  not  requiring  an  elaborate  apparatus 
and  a  large  crew  of  men  to  operate  it;  and  consequently  it  can  be 
used  where  but  a  few  joints  are  to  be  welded. 

Bonding  and  Return  Circuits.  When  the  track  ra'ls  are 
used  as  the  conductors,  as  is  usually  the  case,  it  is  necessary  to  see 
that  the  electrical  conductivity  of  the  rail  joints  does  not  offer  too 
high  a  resi.stance  to  the  passage  of  the  current.  For  this  reason, 
when  bolted  or  angle-bar  joints  are  used,  the  rails  are  bonded  together 
by  means  of  copper  bonds.  It  was  soon  found  after  electric  roads 
were  in  use  a  short  time,  that  unless  the  rail  ends  were  so  bonded, 
the  resistance  of  the  joints  was  so  great  as  to  cAuse  great  loss  of  power 
in  the  track.     First,  small   iron  bonds  were  used;  but  these   l)()nds 


ELECTRIC    RAILWAYS 


89 


were  so  insufficient  that  large  copper-wire  bonds  soon  began  to  be 
use;! ;  and  at  the  present  time,  on  large  roads,  bonds  of  heavy  copper 
cable  ai'c  common.  The  resistance  of  a  steel  rail,  such  as  used  in 
city  streets,- is  about  eleven  times  that  of  copper.  In  order  to  secure 
as  great  carrying  capacity  at  the  rail  joint  as  is  afforded  l)y  the  un- 
broken rail,  it  is  therefore  necessary  to  install  bonds  having  a  total 

cross-section  j\  that  of  the  rail. 
Where  welded  joints  are  used,  bond- 
ing is  unnecessary,  except  at  crossings 
and  switches  where  l)olted  joints  are 
employed.  Where  track  is  welded, 
however,  cross  bonds  should  be  put  in 
at  frecjuent  intervals  from  one  rail  to 
another,  and,  if  the  track  is  double, 
from  one  track  to  the  other,  so  that  if  one  of  the  track  rails  breaks  at 
a  joint  there  will  be  a  path  around  the  break  for  the  current. 


Copper  Wire 


~Channe/  Pin 
Fig.  W).    C'lmnuel  Piu  Boud. 


L 


i--*i 
I  I 


a 


^^<!)^mii!^^MV^^>\\y!;^\;i^^^^^ 


Fig.  81.    Chicago  Rail  Bond. 


A  great  many  schemes  have  been  devised  to  insiu'e  good  con- 
tact between  the  copper  bond  and  the  rail,  as  the  terminal  is  the 
weak  point  in  anv  bond.  One  of  the  earliest  and  most  efficient  of 
.small  bonds  was  made  by  the  use  of  channel  pins,  Fig.  SO.     This 

bond  consisted  of  a  piece  of 

copper  wire    having  its  ends 

placed  in  the  holes  in  the  rail 

ends.     Alongside  this  wire,  a 

channel   pin    was   driven    in. 

The   objection  to  the  channel 

pin  was  the  small  area  of  contact  between  the  copper  l)ond  and  rail. 

Next  after  the  channel  pin  came  the  Chicago  type  of  bond, 

Fig.  ,S1,  which  is  a  jMece  of  heavy  copper  wire  with  thimbles  forged 

on  the  ends.     These  tliimbles  were  placed  in  accurately  fitted  holes 


Fig.  83.    Kail  Bond. 


•M^  ELECTRIC    RAILWAYS 


ill  the  I'ail  (.'inlN,  iiiid  :i  wcdj^r-sliiijjrd  steel  j)iii  was  <lri\eii  into  the 
t!iinil)les  to  expand  tlieni  tightly  into  tlu'  hole  in  the  rail.  Several 
other  bonds  nsin<;  modifieatioiis  of  this  jM'ineiple  are  in  use. 

A  type  of  bond  in  very  coininon  nse  consists  of  solid  copper 
rivet-shaped  terminals,  Fi*;.  S2.  Bet\vee:i  these  terminals  is  a  piece 
of  flexible  stranded  coj)j)er  cable,  made  flat  to  ^o  under  the  angle  bars. 
In  one  type  the  terminal  lu<i;s  are  cast  aroimd  the  ends  of  the  cables, 
and  in  anotlier  type  the  cables  are  for<jed  at  their  ends  into  solid 
rivet-like  terminals.  These  terminal  rivets  were  flrst  appiiecl  as 
any  other  rivets,  with  the  use  of  a  rivetin<i  hannner.  Because  of  the 
difficulty  of  thorou<;hly  expandin^jj  such  large  rivets  into  the  holes 
made  for  theni  in  the  rails,  it  has  become  customary  to  compress 
these  rivets  either  with  a  screw  press  or  a  })ortable  hydrauli'-  press, 
which  brings  such  great  pressure  to  bear  on  the  ()])])osite  ends  of  the 
rivet  that  it  is  forced  to  expand  itself  so  as  to  fill  the  hole  in  the  rail 
completely.  Tiiis  expaTision  is  made  possible  by  the  ductile  char- 
acter of  the  copper.  This  great  ductility  characteristic  of  copper, 
however,  has  l)een  the  source  of  one  of  the  difficulties  in  connection 
with  rail  bonding,  because  the  soft  copper  terminal  has  a  tendency 
to  work  loo.se  in  the  hole  made  for  it  in  the  rail.  It  is  practically 
impossible  to  maintain  good  bonding  where  the  rail  joints  are  .so 
loo.se  as  to  allow  consitlerable  motion  between  the  rail  ends. 

Several  types  of  bonds  have  been  introduced,  in  which  the 
contact  between  the  rail  and  bond  is  marie  by  an  extra  piece  or 
thimble. 

Another  method  of  expanding  bond  terminals  into  the  holes 
made  to  receive  them,  is  that  employed  in  the  (General  Electric 
Company's  bond.  In  it  a  .soft  pin  in  the  center  of  the  terminal 
is  expanded  by  compression  of  the  terminal  so  that  it  forces  the 
copper  surrotmding  it  outward.  The  copper  terminal,  in  expanding 
to  fill  the  hole,  is  therefore  backed  by  the  .steel  center  ])in. 

All  t\'pes  of  bonds  must  be  installed  with  great  care  if  they 
are  to  be  efficient.  Unle.ss  the  bond  terminal  thoroughly  fills  the 
hole  and  is  tightly  expanded  into  it,  moisture  will  creep  into  the 
space  between  the  copper  and  the  iron,  and  the  copper  will  become 
coated  with  a  non-conducting  scale  which  destroys  the  conductivity 
of  the  contact. 


ELECTKIC    RAILWAYS  91 


The  })la.sfic  rail  hoiid,  so  ('alle<l  hecause  it  depends  f:)r  the  contact 
l)etween  the  rail  and  the  bond  upon  a  plastic,  putty-like  alloy  of 
mercury  and  some  other  metal,  is  applied  in  a  number  of  different 
ways.  One  form  consists  of  a  strip  of  copper  held  by  a  spring  against 
the  rail  ends  under  the  fish-plate.  The  rail  ends  at  the  point  of  con- 
tact with  this  strip  of  copper  are  amalgamated  and  made  bright  by 
the  use  of  a  mercury  compound  similar  to  the  plastic  alloy.  These 
points  of  contact  are  then  daubed  with  plastic  alloy,  and  the  copper 
l)ond  plate  applied.  It  is  not  necessary,  with  any  form  of  plastic 
bond,  that  the  mechanical  contact  be  unyielding,  as  the  amalgamated 
surfaces  with  the  aid  of  the  plastic  alloy  between  them,  maintain  a 
good  conductivity  in  spite  of  any  slight  inotion.  The  plastic  alloy 
can  be  applied  in  a  number  of  other  ways,  one  of  which  is  to  drill  a 
hole  forming  a  small  cup  in  the  rail  base  in  adjacent  rail  ends,  fill 
these  cups  with  plastic  alloy,  and  l)ridge  the  space  between  them 
with  a  short  copper  bond  having  its  ends  projecting  down  into  the 
cups. 

Resistance  of  the  Track.  The  resistance  of  the  return 
circuit  is  usually  much  higher  than  it  should  be  owing  to  the  bad 
contact  of  the  bonds.  The  resistance  of  rails  varies  greatly  with  the 
proportions  of  carbon,  manganese  and  phosphorus.  The  following, 
figures,  however,  may  be  regarded  as  the  average. 

Weight  per  Yard.  Resistance  Single  Rail  per  INIile. 
50  .  02.53  ohms 

60  .0211      " 

70  .0180     " 

80  .0159     " 

90  .014 

A  track  laid  with  continuous  rails  as  in  the  case  of  welded  joints, 
would  have  one-half  the  resistance  given  since  there  are  two  rails 
to  be  considered. 

Tests  of  new  unbonded  track  constructed  with  rails  60  feet 
long  show  that  the  joints  cause  an  increase  of  .25  '^hms  or  more  per 
mile. 

Several  roads  in  testing  bonds  consider  a  bond  good  when  the 
bond  and  one  foot  of  the  rail  over  it  have  a  resistance  equal  to  five 
feet  of  the  solid  rail. 


92 


ELECTRIC    RAILWAYS 


Supplementary  Return  Feeders.  On  some  large  roads  it  is 
iiecessary  to  run  aclclltional  return  feeders  from  the  power  house  to 
various  points  on  the  system,  to  supplement  the  conductivity  of 
the  rails.  Otherwise  the  track  rails  near  the  power  house  would 
have  to  carry  all  the  current,  and  in  some  cases  there  are  not  enough 
such  lines  of  track  passing  the  power  house  to  do  this  properly. 
Sometimes  these  feeders  are  laid  underground  in  troughs;  sometimes 
they  are  laid  hare  in  the  ground,  and  sometimes  on  overhead  pole 
lines.  When  laid  in  the  ground,  fretjuently  old  rails  are  u.sed  in.stcad 
of  copper  or  aluminum  cables.  The  old  rails  are,  of  course,  thor- 
oughly bonded  togethei  with  bonds  giving  a  conductivity  nearly 
equal  to  that  of  the  unbroken  rail. 

FEEDER   SYSTEMS. 

There  are  two  general  schemes  of  direct  current  feeding  in  com- 
mon use.  One  of  these  is  shown  in  Fig.  S3.  Here  the  trolley  wire 
is  continuous  and  is  fed  into  at  different  points.     The  long  feeders 


-Trolley 


Fig.  83. 

supplying  the  more  distant  portion  of  the  road  are  larger  than  those 
supplying  the  trolley  near  by,  so  as  to  maintain  as  nearly  as  is  feasible 
the  same  potential  the  entire  length  of  the  line.  With  such  a  system 
of  feeding,  in  order  to  maintain  absolutely  the  same  voltage  at  all 
points,  it  would  be  necessary  to  have  just  one  trolley  feeder  and  that 
feeding  into  the  extreme  end  of  the  line  farthest  from  the  power 
station  and  further  to  make  the  resistance  per  1,000  ft.  of  trolley 
and  feeder  the  same  as  the  resistance  per  1 ,000  ft.  of  the  track  return 
circuit.  The  plan  shown  in  Fig.  83  evidently  does  not  fully  carry 
out  these  rather  impracticable  recjuirements  but.  is  in  the  nature 
of  a  compromise,  giving  a  higher  potential  near  the  power  station 
than  at  distant   ])oints  but  neverthele.ss  much  mor^  even   potential 


ELECTRIC    RAILWAYS 


93 


than  if  the  heaviest  feeders  were  feecHni;'  into  the  trolley  near  the 
power  house. 

The  other  plan,  shown  in  Fig.  S4,  divides  the  trolley  wire  into 
sections  and  feeds  each  section  through  a  .separate  feeder  which  is 
calculated  of  such  size  as  to  maintain  the  same  voltage  on  all  the 
sections  with  the  ordinary  load. 

In  calculating  a  feeder  .sy.stem  a  certain  probable  load  is  assumed 
at  certain  points  along  the  line.  This  load  will  manifestly  depend 
on  the  size  and  number  of  cars  in  operation,  grades  and  many  local 
conditions. 


§ 


■  iMiie- 


'^a  Mites 


iz: 


■  £  Miles 


Drop  in  rail 
secti<>n 

Total  drop in 
rail 

Drop  in  trol- 
ley  

Drop  in  feed- 
er  

Resistance 
feeder 

Feet  per  olina    72.53 

Size  of  wire..  No.  1 


3.1  Volts 

3.1  " 
20.5  " 
36. 1  " 
.728  Ohms 


lies  ■ 


-«+« — /  Miie 


n 


^ 


-a  Miles- 


■  e  Miles  - 


Fig.  84. 

2.1  Volts 

1.05    Volts 

.5.2      " 

6.25     " 

20.5      " 

20.5        " 

'34.3      " 

33.25      " 

.686  Ohms 
23000 
2.50.U00  C.  M. 

.6&5   OJmis 

39700 
420.000   C.  U. 

The  following  example  will  show  the  method  pursued.  The 
figures  resulting  from  the  calculations  are  placed  immediately  below 
the  sections  to  which  they  refer  in  Fig.  84.  The  rails  are  assumed 
to  be  70  pound  to  the  yard.  These  have  a  resistance  of  about  .018 
ohms  per  mile.  Adding  one-sixth  for  additional  resistance  of  bonds 
gives  .021  and  since  the  track  is  composed  of  two  rails  the  resistance 
of  the  track  will  be  one  half  of  this  or  .0105  ohms  per  mile. 

The  maximum  drop  in  any  section  occurs  when  the  car  is  farthest 
from  the  power  house.  Each  car  is  assumed  to  take  50  amperes 
and  the  feeders  are  to  be  so  designed  as  to  allow  a  10  per  cent  or 
60  volts  drop. 

The  current  in  the  two  miles  of  track  nearest  the  power  house 
is  l.')0  amperes,  in  the  next  section  100  amperes,  and  in  the  last  .section 
50  amperes.  The'dropin  each  section  is  as  shown.  The  drop  in  the 
trolley  which  is  00  wire  is,  in  each  section,  20.5  volts.     Subtracting 


94 


ELECTRIC    RAILWAYS 


from  00  volts  the  drop  in  tlie  return  circuit  and  trolley,  gives  the 
allowahle  drop  in  the  feeder. 

Tlie  resistance  of  each  feeder  can  l)e  calculated,  since  the  current 
in  each  one  is  50  amperes.  The  first  feetler  is  one  mile  long,  the 
second  3  miles  and  the  third  5  miles,  and  with  these  figures  the  feet 
per  ohm  can  be  computed.  The  size  of  wire  may  be  obtained  by 
reference  to  a  table  of  copper  wire  resistances. 

BLOCK  SIGNALS  FOR  ELECTRIC  RAILWAYS. 

The  simplest  block  signal  used  by  electric  roads  is  a  hand- 
operated  one  constructed  on  the  principle  shown  in  the  diagram  Fig. 
85.  A  double  throw  switch  is  placed  at  each  terminal  of  the  section 
of  track  that  is  to  be  protected. 

Tro//ey 


LgmfiS 


LarPfs 


T  Ground 


Fig.  85. 


Crouna 


o 


■4 


The  switches  have  no  central  position,  the  knife  blade  always 
making  contact  with  one  or  the  other  of  the  terminals  shown.  If 
the  lamps  are  lighted,  throwing  either  one  of  the  switches  w'ill  put 
them  out.  If  they  are  not  burning,  they  will  be  lighted  by  throwing 
either  one  of  the  switches. 

A  motorman  on  reaching  a  section  of  track  finding  the  lamps 
not  burning  throws  the  switch.  Lamps  now  burn  in  each  switch 
box  and  show  that  the  section  is  in  use.  On  arriving  at  the  other 
terminal  of  the  block  the  switch  is  thrown,  extinguishing  the  lights 
and  showing  that  the  block  is  clear. 

Automatic  signal  systems  have  been  devised  on  the  same  prin- 
ciple, in  which  magnets,  operated  by  contacts  made  by  the  passage 
of  the  trolley  wheel,  cause  the  lamps  to  be  lighted  and  extinguished 
automaticallv. 


ELECTRIC    RAILWAYS  95 

ELECTROLYSIS. 

Muoh  has  been  said  about  the  possibiHties  of  electrolysis  of 
uiKlergroiind  metal  by  the  action  of  the  return  current  of  electric 
railways,  when  such  railways  are  operated  with  grounded  circuits, 
as  they  usually  are.  If  electric  current  is  passed  through  a  licpiid 
from  one  metal  electrode  to  another,  electrolysis  will  take  place; 
that  is,  metal  will  be  deposited  on  the  negative  pole,  and  the  posi- 
tive pole  or  electrode  will  be  dissolved  by  becoming  oxidized  from 
the  action  of  the  oxygen  collecting  at  that  pole. 

In  an  electric-railway  retm-n  circuit,  there  is  necessarily  a  dif- 
ference of  potential  l)etween  the  rails  at  outlying  parts  of  the  system 
and  the  rails  and  other  buried  pieces  of  metal  located  near  the  power 

.        <        ..         Tro/fey   //n  e ^^^ 


DDDDDI  1 


Track 


Fig.  86.    Showing  Electrolytic  Action. 

house.  Just  what  this  total  difference  of  potential  is,  depends  on 
the  loss  of  voltage  in  the  return  circuit.  Thus,  suppose  there  is  25 
volts  drop  in  the  return  circuit  between  a  certain  point  on  the  system 
and  the  power  station.  There  is,  therefore,  a  pressure  of  25  volts 
tending  to  force  the  current  through  the  moist  earth  from  the  rails 
at  distant  portions  of  the  line,  to  the  rails,  water  pipes,  and  other 
connected  metaUic  structures  located  in  the  earth  near  the  power 
station.  The  amount  of  current  that  will  thus  flow  to  earth  in  pref- 
erence to  remaining  in  the  rails,  depends  on  the  relative  resistance 
of  the  rails,  the  earth,  and  the  other  paths  offered  to  the  current  to 
return  to  the  power  house. 

To  take  a  very  simple  case,  let  us  suppose  a  single-track  road, 
Fig.  86,  with  a  power  house  at  one  end,  and  a  parallel  line  of  water 
pipe  on  the  same  street  passing  the  power  house.  If  the  positive 
terminals  of  the  generators  are  connected  to  the  trolley  wire,  the 
current  passes,  as  indicated  by  the  arrows,  out  over  the  trolley  wire 
through  the  cars  and  to  the  rails.     When  it  has  reached  the  rails 


1)0  ELECTRIC    RAILWAYS 


it  has  the  choice  of  two  paths  back  to  tlie  power  house.  One  is 
tlirough  tlie  rails  and  boncHng;  the  other  is  through  the  moist  earth 
to  the  hne  of  water  pipe  and  hack  to  tlie  power  house,  leaving  the 
pipe  for  the  rails,  at  the  power  house.  Should  the  bonding  of  the 
rails  be  very  defective,  consideral)le  current  might  pass  through  the 
earth  to  the  water  pipe. 

Remembering  now  the  principles  of  electrolysis,  we  see  that 
the  oxidizing  action  of  this  flow  of  current  from  the  rails  to  the  water 
pipes  at  the  distant  portion  of  the  road  will  tend  to  destroy  the  rails, 
but  will  not  harm  the  water  pipe  at  that  point,  as  it  will  tend  to 
deposit  metal  upon  it.  ^Yhen,  however,  the  current  arrives  at  the 
power  house,  it  must  in  some  way  leave  this  water  pipe  to  get  back 
to  the  rails,  and  so  to  the  negative  terminals  of  the  generators. 

Here  we  see  that  there  is  a  chance  for  electrolysis  of  the  water 
pipe,  because  at  this  point  the  water  pipe  forms  the  positive  elec- 
trode, which  is  the  one  likely  to  be  oxidized  and  destroyed.  This 
very  simple  case  is  taken  merely  for  illustration.  In  actual  prac- 
tice the  conditions  are  never  so  simple  as  this,  for  there  are  various 
pipes  located  in  the  ground  running  in  various  directions,  which 
complicate  the  case  very  much;  l)ut  we  can  see  from  this  simple 
example  that  the  principal  place  electrolysis  of  water  pipe  is  to  be 
feared  is  at  points  where  a  large  volume  of  current  is  leaving  the 
water  pipe  to  take  to  some  other  conductor. 

As  an  indication  of  how  much  current  is  likely  to  be  leaving 
the  water  pipes  at  various  points,  it  is  customary  to  measure  the 
voltage  between  the  water  pipes  and  the  electric  railway  track  and 
rails.  When  this  voltage  is  high,  it  does  not  necessarily  mean  that 
a  large  volume  of  current  is  leaving  the  water  pipes  at  the  point 
where  these  pipes  are  several  volts  positive  with  reference  to  the 
rails;  but  such  voltage  readings  indicate  that,  if  there  is  a  path  of 
sufficiently  low  resistance  through  the  earth,  and  if  the  moisture  in 
the  earth  is  sufficiently  impregnated  with  salts  or  acids,  there  will 
be  trouble  from  an  electrolytic  action  due  to  a  large  flow  of  current. 
There  is  obv-iously  no  method  of  measuring  exactly  the  amount  of 
current  leaving  a  water  pipe  at  any  given  point,  since  the  pipe  is 
buried  in  the  earth.  A'oltmeter  reatlings  between  pipes  and  rails 
simply  serve  to  give  an  indication  as  to  where  there  is  likely  to  be 
trouble  from   electrolysis.     The  danger  to  underground  pipes  and 


ELECTRIC    liAILWAYS  97 

other  metallic  structures  from  electrolysis  has  been  much  over- 
estimated by  some  people,  as  the  trouJ)le  can  be  overcome  by  proper 
care  and  attention  to  the  return  circuit.  Trouble  from  electrolysis, 
however,  is  sure  to  occur  unless  such  care  is  given. 

Prevention  of  Electrolysis.  Remedies  for  electrolysis  may 
be  classified  under  two  heads — general  and  specific.  The  general 
remedy  is  obviously  to  make  the  resistance  of  the  circuit  through 
the  rails  and  supplementary  i-eturn  feeders  so  low  that  there  will 
be  but  little  tendency  for  the  current  to  seek  other  conductors,  such 
as  water  and  gas  pipes  and  the  lead  covering  of  underground  cables. 
This  remedy  consists  in  heavy  bonding,  in  ample  connections,  around 
switches  and  special  work  where  the  bonding  is  especially  liable  to 
injury,  and  in  additional  return  conductors  at  points  near  the  power 
house  to  supplement  the  conductivity  of  the  rails. 

It  is  important  that  all  rail  bonds  be  tested  at  intervals  of  six 
months  to  one  year  in  order  that  defective  bonds  may  be  located 
and  renewed,  as  a  few  defective  bonds  can  greatly  lower  the  efficiency 
of  an  otherwise  low-resistance  circuit. 

The  specific  remedy  for  electrolysis  which  may  be  ap])lied  to 
reduce  electrolytic  action  at  certain  specific  points,  consists  in  con- 
necting the  water  pipe  at  the  point  where  electrolysis  is  taking  place, 
with  the  rail  or  other  conductor  to  which  the  current  is  flowing. 
Thus,  for  example,  if  it  is  found  that  a  large  amount  of  current  is 
leaving  a  water  pipe  and  flowing  to  the  rails  or  to  the  negative  return 
feeders  at  the  power  house,  the  electrolytic  action  at  this  point  can 
obviously  be  stopped  by  connecting  the  water  pipe  with  the  rails 
by  means  of  a  low-resistance  copper  wire  or  cable,  thereby  short- 
circuiting  the  points  between  which  electrolytic  action  is  taking 
place.  There  are  certain  cases  in  which  it  is  advisable  to  adopt 
such  a  specific  remedy.  It  should  be  remembered,  however,  that  a 
low-resistance  connection  of  this  kind,  while  it  reduces  electrolysis 
at  points  near  the  power  house,  is  an  added  inducement  to  the  ciu*rent 
to  take  to  the  water  pipes  at  points  distant  from  the  power  house, 
because  of  the  decrease  in  resistance  of  the  water-pipe  path  to  tb.e 
power  house  resulting  from  the  introduction  of  the  connection  between 
the  water  pipe  and  the  negative  return  feeder  at  the  power  house. 
With  the  water  pipes  connected  to  the  return  feeders  in  the  vicinity 
of  the  power  house,  the  current  which  flows  from  the  rails  to  the  water 


98  ELECTKIC    KAILWAYS 

])ij)e.s  at  points  distant  from  tlie  j)o\ver  house  will  ohviously  cause 
electrolysis  of  the  rails  but  not  of  the  water  pipes,  since  th.e  ciuTent 
is  passinor  from  the  earth  to  the  pipe,  antl  the  pipe  is  ne<;ative  to  the 
earth.  In  this  case  the  principal  (lano:er  is  that  the  high  resistance 
of  the  joints  between  the  lengths  of  water  pipe  will  cause  current  to 
fiow  through  the  earth  around  each  joint,  as  indicated  on  some  of  the 
joints,  Fig.  86,  and  will  cause  electrolytic  action  at  each  joint.  It 
is  evident,  however,  that  the  conditions  of  the  track  circuit  and 
bonding  must  be  very  bad  if  current  would  flow  over  a  line  of  water 
j)ipe,  with  its  high-resistance  joints,  in  sufficient  volume  to  cause 
electrolysis,  in  preference  to  the  rail-return  circuit,  especially  since 
ordinarily  the  resistance  offered  to  the  flow  of  current  over  the  water 
pipes  back  to  the  power  house  must  include  the  resistance  of  the 
earth  between  the  tracks  and  water  pipes. 

It  is  usuallv  considered  inadvisable  to  connect  tracks  and  water 
pi])es  at  points  distant  from  the  power' house,  because  of  the  danger 
of  electrolysis  at  water-pipe  joints,  as  just  explained. 

IMethods  of  testing  rail  bonds  in  the  track  will  be  explained 
luider  the  head  of  "Tests." 

POWER  SUPPLY  AND  DISTRIBUTION. 

Direct=Current  Feeding.  As  already  explained,  the  majority 
of  electric  railways  are  operated  on  a  .')()0-volt  constant-potential 
direct-current  system  with  a  ground  return.  A  constant  potential 
of  450  to  .550  volts  is  maintained  between  the  trolley  wire  and  track. 
Where  the  trolley  wire  is  not  sufficient,  additional  feeders  are  run 
from  the  power  house  and  connected  to  the  trolley  wire,  the  number 
V  of  feeders  depending  on  the  distance  from  the  power  house  and  the 
traffic. 

Booster  Feeding.  Boosters  are  sometimes  used  on  long 
feeder  lines  where  there  is  a  heavy  load  only  a  small  portion  of  the 
time.  These  boosters  are  direct-current  dMiamos  that  are  con- 
nected in  series  with  the  feeder  upon  which  the  voltage  is  to  be 
raised  above  the  regular  power-house  voltage.  The  booster  may 
be  driven  either  by  a  small  steam  engine  or  by  an  electric  motor. 
The  simplest  form  of  booster  is  a  series-wound  dynamo.  A  booster 
armature  must,  of  course,  be  of  sufficient  current  capacity  to  pass 
iill   the  current   that   will   be   required   on   its   feeder.     The  voltage 


ELECTRIC    RAILWAYS  99 

yielded  by  this  dynamo,  plus  the  power-station  voltage,  is  the  voltage 
of  the  boosted  feeder  as  it  leaves  the  power  house.  Supposing  that 
a  series-wound  booster  will  give  125  volts  at  full  load;  it  is  obvious 
that  being  series-wound  it  will  give  no  voltage  at  no  load.  The 
voltage  will  increase  approximately  as  the  load  on  the  feeder  increases; 
and  since  the  drop  in  voltage  on  the  feeder  for  which  the  booster  is 
to  compensate  also  varies  with  the  load,  the  action  of  the  booster  is 
simply  to  add  sufficient  voltage  to  its  feeder  at  any  instant  to  com- 
pensate for  the  line  loss  upon  that  feeder  and  to  maintain  approxi- 
mately constant  potential  at  the  far  end  of  the  feeder.  Boosters 
raising  the  power-station  voltage  of  a  feeder  more  than  250  volts 
above  the  normal  power-station  voltage,  are  not  common,  though 
cases  are  on  record  where  a  feeder  has  been  boosted  as  high  as  1,100 
volts  above  the  power-station  voltage.  Since  all  the  power  used 
in  driving  a  booster  is  wasted  in  line  loss,  this  method  of  feeding  is 
not  economical;  but  where  used  only  a  few  days  out  of  the  year  it  is 
sometimes  to  be  preferred  to  a  heavy  investment  in  feeders.  The 
investment  in  feeders  might  involve  more  interest  charges  than  the 
cost  of  power  wasted  in  booster  feeding  would  amount  to. 

Alternating=Current  Transmission.  High-tension  alternat- 
ing-current transmission  to  substations,  with  direct-current  dis- 
tribution from,  substations,  is  extensively  used  on  long  interurban 
roads,  and  on  large  city  street-railway  systems  w^here  power  is  to 
be  distributed  over  a  wide  area.  In  such  cases  the  power  house  is 
equipped  with  alternating-current  dynamos  supplying  high-tension 
three-phase  alternating  current  to  high-tension  transmission  lines 
or  feeders.  These  high-tension  feeders  are  taken  to  substations 
located  at  various  points  on  the  road,  where  the  voltage  is  reduced 
by  step-down  transformers;  and  these  transformers  supply  current 
to  operate  rotary  converters,  which  convert  from  alternating  to 
direct  current  for  use  on  the  trolley. 

The  advantage  of  this  system  of  high-tension  distribution  is 
that,  owing  to  the  high  transmission  voltage,  there  is  but  a  small 
loss  in  the  high-tension  lines,  which  lines  can  be  made  very  small, 
and  will  thus  involve  but  little  copper  investment.  The  substations 
can  be  located  at-  frequent  intervals,  so  that  the  distance  the  500-volt 
direct-curreitt  must  be  conducted  to  supply  the  cars  is  not  great. 
Current  from  one  power  house  can  thus  be  distributed  over  a  very 


100 


ELECTRIC    RAILWAYS 


larere  system  in  cases  where,  if  the  oOO-voU  (hrect-ciirrent  system 
of  (hstribution  \yere  used,  the  cost  of  feeders  for  distributing  such  a 
h)^v-yoltage  current  would  be  prohibitiye.  AVere  the  ahernating-cur- 
rent  high-tension  scheme  of  distribution  not  used,  it  would  be  neces- 


Higf^  Tensiort 
D.  c.  Feec/er- 


ifA/RMOUNT 


Broad - 
/Nipple. 


/NOMf^APOLIS 

Fig.  87.    Diagram  of  Distributing  Sj'stem. 

sary  to  haye  a  number  of  small  power  houses  at  yarious  points  on 
the  system  instead  of  one  large  power  house.  The  cost  of  operation 
of  seyeral  small  power  plants  per  kilowatt  output,  is  likely  to  be 
much  greater  than  that  of  one  large  power  plant.  The  first  cost 
of  the  alternating-current  distributing  system,  including  power  house 


Ei^ECTRIC    RAILWAYS.  101 

and  substations,  is  likely  to  be  considerably  higher  than  would  be 
the  cost  of  a  number  of  small  power  houses;  but  in  cases  where  alter- 
nating-current distribution  has  been  installed,  it  has  been  figured 
that  the  cost  of  operation  of  the  central  power  house  with  alternating- 
current  distribution  would  be  sufficiently  low  as  compared  with 
several  small  ones  to  pay  more  than  the  interest  on  this  extra  invest- 
ment. 

A    System    of    Distribution    for    an    Interurban     Railway. 

The  typical  features  of  a  high  tension  system  of  distribution  for  an 
extensive  interurban  railway  system  are  shown  in  Fig.  S7,  which 
represents  the  electrical  transmission  and  distribution  system  of  the 
Indiana  Union  Traction  Company.  The  central  power  station  at 
Anderson  feeds  into  thirteen  rotary  converter  substations  from  7 
to  65  miles  distant  from  the  power  house.  The  substations  east  of 
Indianapolis  are  fed  at  16,000  volts  and  are  placed  about  11  miles 
apart.  The  substations  due  north  of  Indianapolis  are  located  at 
intervals  of  about  17  miles  and  are  fed  at  30,000  volts. 

The  power  station  at  Anderson  has  a  total  capacity  of  5,000  K.  V\ . 
The  substations  vary  in  capacity  from  250  to  1 ,500  K.  W. 

Efficiency  of  Transmission  Systems.  The  average  efficiency 
of  a  high  tension  transmission  system  for  a  certain  interurban 
electric  railway  system  are  given  below.  Current  was  generated  at 
380  volts.  The  step-up  transformers  raised  it  to  a  potential  of  16,000 
volts  at  which  pressure  it  was  transmitted  to  eight  substations  at 
distances  from  10  to  40  miles  from  the  power  station.  It  was  then 
stepped  down  to  380  volts  and  converted  to  direct  current  by  a  rotary 
converter.  The  tests  extended  over  a  period  of  three  days.  The 
efficiency  of  the  step-up  transformers  was  95  per  cent;  of  the  high 
tension  line  92.9  per  cent;  of  the  step-down  transformers  95  per  cent; 
and  of  the  rotary  converters  88  per  cent;  giving  a  total  efficiency  of 
the  transmission  system  of  73.5  per  cent. 

Power  House  Location.  A  power  house  is  usually  located 
where  coal  and  water  supply  can  be  cheaply  obtained.  For  this 
reason  it  is  placed  either  on  some  line  of  railroad  or  where  coal  can. 
be  taken  to  it  over  the  electric  railwav. 

As  it  is  always  desirable  to  operate  the  engines  in  connection 
with  condensers,  on  account  of  the  saving  in  fuel,  which  is  approx- 
imately 20  per  cent  with  condensers,  power  stations  are  located, 


102  ELECTRIC    RAILWAYS 


when  possible,  near  rivers  and  ponds  from  which  a  large  supj/ly  of 
cold  water  for  condensation  of  exhaust  steam  can  be  obtained. 
Where  no  such  natural  water  supply  is  available,  it  has  become 
customary  to  provide  means  for  artificially  coolino-  a  sufficiently 
large  supplv  of  water  for  condensation.  One  method  is  to  erect  a 
numijer  of  towers,  so  constructed  that  the  water  when  pimiped  to 
the  top  will  fall  through  a  structure  that  breaks  the  water  up  into 
fine  spray  as  it  falls,  thus  alU)wing  it  to  cool  by  evaporation  so  that 
it  can  be  used  again  for  the  condensers  when  it  arrives  at  the  bottom 
of  the  tower.  AVhere  more  room  is  a^•ailable,  ponds  are  sometimes 
excavated  near  the  power  house,  and  the  water  is  made  to  flow  back 
and  forth  through  a  series  of  troughs  located  above  the  pond,  and 
it  is  thus  cooled^ 

Where  a  power  station  is  of  the  direct-current  type,  operating 
at  500  to  600  volts,  it  is  desirable  to  have  it  as  near  the  center  of 
electrical  distribution  as  possible,  in  order  to  keep  down  the  amount 
of  investment  in  the  feed  wire;  but  it  is  more  important  to  have 
it  located  near  a  cheap  coal  and  water  supply  than  exactly  at  the 
center  of  distribution. 

It  is  also  desirable  to  have  the  station  located  where  there  is 
room  for  coal  storage,  on  account  of  the  dmnces  for  interruption 
of  the  coal  supply  by  strikes,  railroad  blockades,  and  other  causes 
beyond  the  company's  control.  The  continuity  of  the  coal  supply 
is  also  another  argument  against  placing  the  station  where  depend- 
ence must  be  placed  upon  wagons  or  inadeciuate  railroad  facilities. 

Coal  handling,  after  the  coal  has  reached  the  station,  is  done 
bv  hand  in  the  smaller  power  stations;  but  in  larger  power  stations 
it  lias  come  to  be  the  general  practice  to  do  as  much  of  the  handling 
as  possible  by  means  of  automatic  coal  conveyors.  The  most  elab- 
orate power  stations  have  means  for  dumping  coal  from  cars  into 
hoppers,  from  whic-h  it  is  conveyed  by  an  endless  chain  provided 
with  buckets,  called  a  coal  conveyor,  to  storage  bins.  Coal  conveyors 
also  take  the  coal  from  the  storage  bins,  aiul  deposit  it  in  the  hoppers 
of  mechanical  stokers  in  front  of  the  boilers.  Ashes  are  conveyed 
from  under  the  boilers  by  the  s?>me  kind  of  conveyors,  and  are  dumped 
into  hoppers,  whence  they  are  drawn  into  cars  or  wagons  to  ))e 
hauled  away. 


ELECTRIC    KAILWAYS  103 

The  coal,  having  been  deposited  in  hoppers  at  the  boiler  front, 
is  autoniaticallv  fed  into  the  furnaces  by  automatic  stokers.  One 
t\^)e  of  automatic  stoker  in  common  use  is  of  the  chain-grate  or 
link-belt  type,  which  is  constructed  like  an  endless  sprocket  chain, 
with  links  composed  of  heavy  cast-iron  blocks  that  serve  as  grate 
baj's.  This  link  belt  or  chain  is  kept  in  constant,  slow  motion  by 
a  small  stoker  engine  or  motor  which  operates  all  the  stokers  of  a 
line  of  boilers.  The  coal  is  fed  from  the  hopper  on  to  the  chain 
jjrate,  and  the  chain  is  slowly  moved  under  the  boilers.  As  the 
coal  on  that  part  of  the  grate  imder  the  boilers  is  on  fire,  the  fresh 
coal  as  it  enters  the  furnaces  is  soon  ignited.  The  grate  is  run  at 
such  a  rate,  and  the  thickness  of  the  coal  is  so  adjusted,  that  the 
coal  is  burned  to  an  ash  bv  the  time  it  has  traveled  to  the  back  of 
the  furnace.  There  the  grate  turns  down  over  a  sprocket  wheel, 
and  the  ashes  are  dumped  into  the  ash  pit  as  the  grate  revolves. 

The  boilers  in  most  common  use  in  large  American  electric- 
railway  power  houses  are  of  the  water-tube  -  type,  in  which  water  is 
contained  inside  of  a  bank  of  tubes,  the  ends  of  these  tubes  being 
connected  to  drums  or  headers.  The  horizontal  return-tubular  type 
of  boiler  is  used  in  many  of  the  smaller  power  stations,  and  verti- 
cal boilers  are  also  in  use. 

The  engines  in  the  larger  and  more  economical  stations  are 
generally  of  the  Corliss  compound-condensing  type,  running  at 
speeds  of  from  60  to  120  revolutions  per  minute,  according  to  the 
size  of  the  unit.  The  smaller  the  unit,  the  higher  the  speed.  In 
the  smaller  and  older  stations,  simple  Corliss  engines  belted  to 
generators  are  frequently  found,  and  high-speed  engines  also  are 
'.ised.  It  is  the  almost  universal  custom  now,  to  place  the  generator 
ilirectly  on  the  engine  shaft,  making  a  direct-connected  luiit. 

Steam  turbines,  in  which  the  steam  acts  in  jets  against  the 
blades  of  a  turbine  wheel,  are  beginning  to  come  into  use  at  the 
])i-esent  time.  These  turbines  rotate  at  very  high  speed,  the  largest 
and  slowest  speed-units  running  600  r.p.m.,  and  others  at  higher 
rates.  As  the  output  of  any  generator  varies  directly  according 
to  its  speed,  a  very  much  smaller  generator  can  be  used  when  coupled 
to  a  high-speed  steam  turbine,  to  obtain  a  given  output,  than  if  the 
generator  must  be  coupled  to  a  Corliss  steam  engine  which  revolves 
at  very  low  speed.     The  economy  of  the  steam  turbine  at  full  load 


IQi 


ELECTRIC    RAILWAYS 


is  about  that  of  a  compoiind-coiulensing  Corliss  engine,  but  is  better 
on  light  loads  than  the  engine.  Thcv  turbine  requires  less  building 
space  and  a  much  less  expensive  foundation. 

Railway  generators  or  dynamos  for  direct  current  are  usually 
built  with  compound-woimd  fields,  so  that,  as  tlie  load  increases, 


I 

2 


I 


i 


^y/yyyyyyyyy^     w/^^y^^y>^//^y>j^/A       w////////;^7Z7m>//////////////A 


BO/LER 


BO/LfTR    CO 


BO/LER 


Bo/LER  art  I 


y/////////A       y////////////^/A         Y////////////////^//{////?Z'^7m' 


Fig.  88.    Phm  of  P.nvei-  House. 


thev  will  automatically  raise  the  voltai-e  at  their  terminals  to  com- 
pensate  for  the  drop  in  the  feeders  and  to  maintain  a  constant  poten- 
tial at  the  cars.  Thus,  if  the  line  loss  on  a  system  is  10  per  cent,  or 
50  volts  at  full  load,  the  generators  will  be  provided  with  shunt  fiekls 
of  sufficient  strength  to  give  500  volts  at  no  load,  and  with  series 
field  coils  wliich  will  add  to  the  field  strength  enough  to  give  550 
volts  at  full  load.     The  amount  of  "compounding" — which  is  the 


ELECTRIC    RAILWAYS  105 


term  applied  to  this  method  of  increasing  voltage — may  be  any 
amount  within  reasonable  limits.  The  pressin-e  maintained  at 
difierent  companies'  electric-railway  power  houses  varies,  but  is 
usuallv  ])etween  500  and  GOO  volts. 

AIternating=Current  Generators.  Alternating-current  gen- 
erators used  for  generating  alternating  current  to  be  distributed  at 
high  tension,  are  generally  constructed  to  give  a  three-phase  cur- 
rent at  25  cycles  per  second.  Th6  voltage  of  these  alternating- 
current  generators  is  sometimes  the  voltage  at  which  the  power  is 
to  be  transmitted,  if  the  distances  are  not  too  great.  A  number 
of  stations  have  alternating-current  generators  giving  6,600  volts 
at  their  terminals,  which  is  a  voltage  well  adapted  to  high-tension 
distribution  within  the  limits  of  a  large  city.  However,  genera- 
tors giving  11,000  volts  at  their  terminals  are  now  becoming  com- 
mon. For  higher  voltages  than  this,  it  is  considered  necessary  to 
use  step-up  transformers,  in  order  to  raise  the  voltage  to  the  proper 
pressure  for  transmission  over  long  distances.  In  such  cases  there 
is  no  object  in  having  a  high  generator  voltage.  At  such  stations 
the  voltage  of  the  generators  adopted  may  be  anything  desired, 
and  it  varies  according  to  the  ideas  of  the  constructing  engineer. 
Voltages  of  400,  1,000,  and  2,.300  are  among  those  in  most  com- 
mon use. 

Double=Current  Generators.  Double-current  generators  are 
sometimes  used,  which  generators  will  give  direct  current  at  a 
commutator  at  one  end  of  the  armature  for  use  on  a  500-volt  direct- 
current  distribution  system  supplying  the  trolley  direct.  The  other 
end  of  the  armature  has  collector  rings  from  which  the  three-phase 
alternating  current  is  obtained,  which  can  be  taken  to  step-up  trans- 
formers and  raised  to  a  sufficient  pressure  for  high-tension  transmis- 
sion to  substations  at  distant  parts  of  the  road.  The  same  generator 
can  therefore  be  used  on  both  the  direct-current  and  the  high-tension 
alternating-current  distribution. 

General  Plan  of  Power  Stations.  The  general  plan  of  an 
electric-railway  power  station  is  usually  such  that  the  building  can 
be  extended  and  more  boilers,  engines  and  generators  added  without 
<listurbing  the  symmetrical  design  of  the  station.  Thus,  the  boilers 
and  engines  are  placed  as  in  Fig.  88,  in  parallel  rows,  although  almost 
invariably  in  different  rooms  separated  by  a  fire  wall.     By  adding 


im 


ELECTRIC    RAILWAYS 


to  the  row  of  engines  and  to  the  row  of  boilers,  the  station  capacity 
can  be  increased.  Other  arrangements  are  sometimes  re(|uired  by 
circumstances;  but  this  is  the  most  common  arrangement  and  gives 
the  greatest  capacity  witli  the  minimum  amount  of  steam  piping. 
Large  stations  are  sometimes  constructed  with  a  lioiler  room  of 
several  floors  and  with  boilers  on  each  floor,  in  order  to  save  ground 
space  and  bring  the  boilers  near  to  the  large  engine  imits  so  that  there 
will  not  be  an  excessive  amount  of  steam  piping. 

Switchboards.  Direct-cur- 
rent stations  have  switchboards, 
which  may  be  considered  under 
two  general  classes  —  gcncrafor 
hoards  and  feeder  boards.  Each 
iward  consists  of  panels. 

Generator  D.  C.  Panels. 
The  generator  panel  usually  con- 
tains an  automatic  circuit  breaker 
which  will  open  the  main  circuit 
to  the  generator  in  case  of  an 
overload  due  to  a  short  circuit. 
These  circuit  breakers  consist  of 
a  coil  in  the  main  circuit,  which 
acts  upon  a  solenoid.  When  the 
current  in  the  coil  exceeds  a  cer- 
tain amount,  the  solenoid  is 
drawn  in,  and  a  trigger  is  trip- 
ped which  allows  the  circuit 
breaker  to  fly  open  under  the  pressure  of  a  spring.  In  the  General 
Electric  circuit  breaker,  the  main  contact  is  made  by  heavy  cojjper 
jaws,  but  the  last  breaking  of  the  contact  is  made  between  points 
which  are  under  the  influence  of  a  magnetic  field.  This  magnetic 
field  blows  out  the  heaw  arc  that  would  otherwise  be  established. 
On  the  I-T-E,  the  "Westinghouse  and  most  other  types  of  circuit 
breaker,  the  breaking  of  the  contact  takes  place  between  carl)on 
points,  which  are  not  so  readily  destroyetl  by  an  arc  as  are  co])per 
contacts,  and  which  are  more  cheaply  renewed.  The  main  contact 
through  the  circuit  breaker,  in  either  t^-pe,  is  made  between  coj)j,er 
jaws  of  sufficient  cross-section  for  carrying  the  current  without  heating. 


Fig.  89a.    G.  E.  Circuit  Breaker. 


ELECTRIC    RAILWAYS 


107 


These  jaws  open  before  the  current  is  finally  broken  by  the  smaller 
contacts  which  take  the  final  arc. 

In  Fiff.  89a  is  seen  a  General  Electric  c-ii'cuit  breaker  with  the 
magnetic  blow-out  coils  at  the  top,  the  solenoid  at  the  left,  and  the 
handle  for  resetting;  the  circuit  breaker  at  the  bottom.  The  small 
handle  for  tripping  the  circuit  breaker,  when  it  is  desired  to  open 
the  circuit  by  hand,  is  shown  just  under  the  solenoid. 

An  I-T-E  circuit  breaker  is  shown  in  Fig.  896.  This  is  of 
the  type  previously  mentioned,  in  which  the  break  occurs  between 
carbon  contacts  and  there  is  no  magnetic  blow-out. 

In  addition  to  the  circuit 
breaker  there  is  usually  an 
ammeter,  to  indicate  the  cur- 
rent passing  from  the  gener- 
ator; and  a  rheostat  handle, 
geared  to  a  rheostat  back  of 
the  board,  for  cutting  in  and 
out  more  or  less  resistance  in 
the  shunt  field  coils  of  the 
generator  so  as  to  reduce  or 
raise  the  voltage.  There  is 
a  small  switch  for  opening 
and  closing  the  circuit  through 
the  shunt  field  coils. 

The  main  leads  from  the 
generator  pass  through  two 
single-pole  quick-break  knife  switches.  The  most  recent  practice  is  to 
have  the  switches  on  the  switchboard  in  only  the  positive  and  negative 
leads  from  the  generator,  leaving  connection  to  the  equalizer  to  be 
made  by  a  switch  located  on  or  near  the  generator.  However,  all 
three  leads  may  be  taken  to  the  switchboard,  and  a  three-pole  knife 
switch  may  be  used  instead  of  the  positive  and  negative  switches 
spoken  of. 

In  Fig.  90  is  given  a  simple  diagram  of  the  general  relative 
connection  of  generators  and  feeders  in  a  direct-current  railway 
power  station.  It  is  seen  that  the  generators  are  connected  in  parallel 
across  the  positive  and  negative  bus  bar.  There  is  a  third  bus  bar 
— called  an  "ec^ualizing  bus" — which  connects  in  parallel  the  series 


Fig.  S9b.    I-T-E  Circuit  Breaker. 


lus 


ELECTRIC    RAILWAYS 


coils  of  all  the  fjenerator  fields.  Tlie  object  of  this  ecjualizer  is  to 
prevent  the  weakening  of  the  series  field  of  any  one  generator,  so  as  to 
allow  it  to  take  current  and  to  act  as  a  motor  instead  of  as  a  generator. 
Starting  Up  a  Generator.  Suppose  that  a  new  generator  is 
to  be  started  up  and  conneated  to  tlie  bus  bars  in  addition  to  others 
already  in  operation.  The  engine  of  that  generator  is  first  brought 
up  to  speed.  The  switch  controlling  the  shunt  field  circuit  is  then 
closed,  causing  current  to  flow  through  the  shunt  fields;  and  the 
generator  begins  to  "build  up,"  its  voltage  gradually  rising  until 
it  approximates  that  upon  the  bus  bars.  Before  the  generator  is 
thrown  in  parallel  with  the    others    by  connecting  it  with  the  bus 


—  Bus 


To  ra/7s 


Fig.  yo.     Connection  of  Generators  and  Feeders. 


bars,  it  is  important  that  its  voltage  be  nearly  the  same  as  that  of 
the  bus  bars.  Otherwise,  when  connected  to  the  bus  bars,  it  might 
take  more  than  its  share  of  the  load;  while,  on  the  other  hand,  if 
its  voltage  were  too  low,  it  might  act  as  a  motor,  taking  current 
from  the  bus  bars.  The  voltage  of  the  bus  bars  in  a  railway  station 
is  constantly  fluctuating,  owing  to  the  varying  load  and  to  the  fact 
that  generators  are  often  compounded,  as  before  mentioned,  in  order 
to  compensate  for  the  line  loss. 

In  order  that  the  voltage  of  the  generator  to  be  thrown  in  shall 
var\'  in  accordance  with  the  bus  bar  voltage,  the  next  step  in  the 
operation  is  to  close  the  positive  switch,  assuming  that  the  equalizer 
switch  on  the  (generator  has  alreadv  been  closed.     This  throws  the 


ELECTRIC    RAILWAYS 


109 


series  fieltl  of  the  new  g-enerator  in  parallel  with  the  series  fields  of 
the  other  generators.  The  voltage  of  the  new  generator  will  there- 
fore vary  just  as  the  voltage  on  the  hiis  bars;  aiul,  hy  adjusting  the 
resistance  of  the  shunt  field,  this  vokage  can  be  adjusted  so  as  to  he 


O 

♦J 

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>. 

> 


•(-I 

&4 


the  same  as  that  on  the  bus  bars.  The  voltages  on  the  bus  bars  and 
on  the  new  generator  are  measured  nsually  by  a  large  voltmeter  on 
a  bracket  at  tlie  end  of  the  generator  switchboard.  By  means  of  a 
voltmeter  plug  ov  of  a  push  button  on  the  generator  panel,  the  volt- 


110  ELECTKir    ^^UL\VAYS 


iDoter  can  !)«•  coiiiiected  t'itluT  to  the  l)U.s  l)ars  or  to  the  new  <feiit'rator. 
Wlien  the  two  voltai^es  are  tlie  same,  the  ne<;ative  switch  of  the  new 
generator  can  l»c  closed,  and  it  will  o|)erate  in  parallel  witli  t!ie  other 
<^enerat<M-s,  takin*:;  its  share  of  the  load.  If  the  attendant  sees  that 
any  generator  is  not  taking;  its  share,  he  can  raise  its  voitafje  l)y  cntting 
out  some  of  the  resistance  in  series  with  its  shunt  Held,  and  this  makes 
that  generator  take  more  load. 

Feeder  Panel.  The  feeder  ])anel  is  sim])ler  than  the  generator 
panel,  since  it  usually  handles  only  tlie  positive  side  of  the  circuit. 
Fre(juently  two  feeders  are  run  on  a  single  panel  side  hy  side.  The 
feeder  panel  has  an  automatic  circuit  breaker,  an  annneter  for  indi- 
cating the  current  on  that  feeder,  and  a  single-pole  switch  for  connect- 
ing the  feeder  to  the  bus  bar.  All  generators  feed  into  a  common  set 
of  bus  l)ars;  and  the  positive  l)us  bar  continues  back  of  the  feed?? 
panels  .so  tiiat  all  feeders  can  draw  current  from  the  bus  bars.  Fig. 
!)]  shows  a  railway  switchl)oard  with  7  feeder  panels  at  tlie  right; 
4  generator  j)anels  at  the  left;  and.  in  the  mid<lle,  a  panel  with  an 
annneter  and  reconhng  wattmeter  for  measuring  total  outj)ut. 

In  .some  .stations  two  and  even  three  sets  of  l)us  bars  are  used, 
as  it  may  be  tlesired  to  operate  different  parts  of  the  system  at  different 
voltages  or  to  feed  a  higher  voltage  to  the  longer  lines  than  to  those 
near  the  station.  In  such  a  case  double-throw  switches  are  provided 
for  connecting  feeders  and  generators  to  either  set  of  bus  bars.     ,£; 

AIternating=Current  Switchboards.  In  an  alternating-cur- 
rent .station,  generator  switchboards  are  radically  different  from 
those  in  a  direct-current  .station.  Practice  in  alternating-current 
generator  switchboards  has  not  yet  l)een  so  fully  standardized  and 
is  not  .so  uniform  as  in  direct-current  railway  switchboards.  There 
is  alwavs,  however,  a  three-pole  main  switch  for  opening  and  clo.s- 
ing  the  main  three  wires  from  the  three-phase  generator.  Auto- 
matic circuit  breakers  are  usually  provided,  as  well  as  indicating 
ammeters  and  wattmeters  to  .show  the  output. 

Indicating  wattmeters,  recording  the  number  of  watt  hours 
passing  through  them,  are  frequently  u.sed  both  on  alternating  and 
direct-current  generator  panels. 

A  station  usually  has  what  is  called  a  "total  load"  panel,  which 
has  a  recording  wattmeter  measuring  the  total  outjnit  of  the  station 


ELECTRIC    KAILWAYS  111 

in  kilowatt  hours.  This  panel  also  has  an  annnctcr  indicating  the 
total  station  load. 

High=Tension  Oil  Switches.  AltcM-natin<^-cnrrcnt  <fencrators 
for  high  voltages  usually  have  oil  switches  to  interrupt  the  main 
circuit,  that  is,  switches  in  which  the  contact  is  made  and  broken 
inider  oil.  These  switches  have  been  found  very  efficient  in  pre- 
venting the  formation  of  a  destructive  arc  upon  tiie  opening  of  a 
high-voltage  circuit,  on  circuits  up  to  fiO.OOO  volts.  Some  of  the 
larger  oil  switches  are  o])erated  by  electric  motors  or  solenoids. 
The  machine-type  oil  switch  of  the  (leneral  Electric  Company  has 
the  motive  power  for  operating  the  switches,  stored  up  in  a  spring. 
The  spring  is  wound  up  by  a  small  electric  motor.  This  motor 
operates  every  time  the  switch  is  opened  or  closed,  and  winds  up 
the  spring  enough  to  compensate  for  the  amount  it  was  unwound 
in  operating  the  switch.  Each  circuit  is  broken  under  oil  in  a  long 
tube,  and  these  tul)es  are  mounted  in  individual  cells,  each  cell 
being  separated  from  the  next  by  a  masonry  wall  so  that  ther^  can 
be  no  flashing  across  from  one  leg  of  the  circuit  to  another  in  case 
of  anv  defect  in  the  switch.  All  the  high-tension  wiring;  to  and 
from  such  switches,  is  taken  either  in  lead-covered  cables,  or  on 
l)us  bars  separated  from  each  other  by  masonry  walls  to  prevent  the 
spread  of  short  circuits.  These  precautions  are  necessary  because 
of  the  great  length  of  arc  that  may  be  established  between  adjacent 
high-tension  conductors. 

Where  alternating-current  generators  of  low^  voltage  are  used 
in  connection  \\'ith  step-up  transformers,  one  practice  is  to  have 
the  switches  for  each  generator  directly  in  the  generator  leads,  l)e- 
tween  the  generators  and  the  step-up  transformers,  in  the  low-voltage 
circuit. 

Another  practice  which  has  recently  been  introduced,  is  to  con- 
sider each  generator  with  its  step-up  transformers  as  a  unit  and  to 
connect  the  generator  permanently  with  its  bank  of  transformers, 
and  to  control  this  unit  l)y  a  single  three-pole  machine-operated 
oil  switch.  In  this  case  there  are  no  switchboard  switches  l)etween 
generators  and  transformers,  and  this  simplifies  the  switchboard 
considerably.  There  must  be  switches  on  the  high-tension  side  of 
the  transformers  in  any  event. 


112  ELECTKIG    KAIJ.WAVS 

The  switchhoanl  for  rotary  converters  in  the  substations  is, 
of  course,  a  combination  of  alternating  and  direct-current  apj)aratus. 
Tlie  direct-current  ends  of  the  rotary  converters  are  treated  ahnost 
exactly  like  direct-current  railway  generators;  and  their  switchboard 
panels  are  similarly  eciuipped,  except  that  usually  there  is  a  rheostat 
that  can  be  connected  in  series  with  the  armature  whereby  a  rotarv 
converter  can  be  brought  up  to  speed  from  a  state  of  rest  by  connecting 
it  with  the  direct-current  bus  bars  of  the  substation. 

The  alternating-current  end  of  the  rotary  converter  is  sup- 
plied through  switches  in  the  alternating-current  leads  from  the 
step-down  transformers.  A  rotary  converter  can  be  started  from 
a  state  of  rest  by  connecting  it  to  the  alternating-current  leads  through 
the  medium  of  compensating  coils  which  reduce  the  voltage.  A  very 
heavy  current  is  refpiired  to  do  this,  as  the  motor  thus  starts  as  a  very 
inefficient  induction  motor  with  a  very  low  power  factor. 


TROLL  Ey 

TFlOLLEy 

TROLLED 

I 

S  A, 

SUBSTAT/ON 
BUS  BARS 

A  ^Circuit  breaker 

A 

=i 

SUBSTATION 
BUS  BARS 

^T-" 

Fif;.  '.fi.    CoiiiKH'tiun  of  Suljs-tatiuiis. 

There  are  usually  but  two  direct-current  feeder  panels  in  a 
substation  of  an  interurban  electric  road.  One  of  these  feeders 
is  to  supply  the  trolley  or  third  rail  extending  in  one  direction  from 
the  substation,  and  the  other  feeds  that  extending  in  the  other  direc- 
tion from  the  substation.  The  trolley  or  third  rail  has  a  section 
insulator  directly  at  the  substation.  When  both  feeders  are  con- 
necte<l  to  the  bus  bars,  it  is  evident  that  this  section  insulator  is  .short- 
circuited  through  the  medium  of  the  substation  bus  bars,  every  sub- 
.stati(m  on  the  line  being  connected  in  this  way,  as  indicated  in  Fig.  92. 
It  is  seen  that,  should  a  short  circuit  occur  on  any  section,  it  would 
open  the  circuit  breakers  at  the  substations  at  both  ends,  and  that 
.section  would  not  interfere  with  the  balance  of  the  road.  At  the 
same  time,  when  the  road  is  in  normal  operation  and  there  is  an 
uiuisuallv  heavv  load  between  aiiv  two  substations,  the  other  sub- 
stations  along  the  line  can  help  out  those  nearest  to  the  load  by  feeding 
through  the  bus  bars  of  the  nearest  su!)station. 


ELECTRIC    RAILWAYS  113 


The  high-tension  apparatus  at  a  sul)station  consists  usually 
of  a  bank  of  high-tension  lightning  arresters;  high-tension  switches, 
for  shutting  off  the  high-tension  current;  and  step-down  transformers, 
for  reducing  from  the  high  transmission  voltage  to  the  370  volts 
connuonly  fed  to  the  alternating-current  end  of  railway  rotary  con- 
verters. 

Storage  Batteries  in  Stations.  Storage  batteries  are  fre- 
quently used  both  in  substations  and  in  direct-current  power  stations. 
They  may  be  connected  directly  across  the  line  and  allowed  to  "float," 
as  it  is  termed ;  or  they  may  be  used  in  connection  with  storage-battery 
boosters,  which  will  cause  the  storage  battery  to  take  the  fluctuations 
in  the  loatl  and  to  give  a  constant  load  on  the  rotary  converters  or 
power  station.  The  action  of  storage-battery  boosters  which  cause 
the  storage  battery  to  be  charged  automatically  at  light  loads  and  to 
discharge  and  assist  the  station  at  heavy  loads,  is  explained  in  the 
paper  on  "Storage  Batteries." 

ALTERNATINQ.CURRENT  SYSTEMS. 

So  far  this  paper  has  been  devoted  almost  entirely  to  electric 
railway  systems  employing  500-volt  direct-current  motors  on  the 
cars,  since  this  is  the  system  almost  universally  employed  on  elec- 
tric railways  at  the  present  time.  There  are,  however,  several  sys- 
tems employing  alternating-current  motors  on  cars,  which  have 
already  been  used  experimentally  and  to  some  extent  commercially. 
Some  of  these  give  promise  of  coming  into  extensive  use. 

Three=Phase  Motors.  On  several  roads  in  Europe  tlu'ce- 
phase  induction  motors  are  employed.  These  induction  motors 
are  operated  by  three-phase  alternating  current  taken  direct  from 
the  trolley  wires.  As  three  conductors  are  necessary,  two  trolley 
wires  are  used,  with  the  rails  as  the  third  conductor.  The  two 
principal  objections  to  the  system  are  the  necessity  of  two  -trolley 
wires,  and  the  fact  that  the  induction  motor  operates  very  much 
like  a  direct-current  shunt  motor  in  that  it  is  a  constant-speed  motor 
and  not  adapted  to  variable-speed  work.  The  power  factor  is  low 
in  starting;  that  is,  a  great  volume  of  current  is  taken,  although, 
owing  to  the  voltage  and  the  current  not  l>eing  in  phase,  the  actual 
energy  consumed  is  small. 


lU  ELECTRIC    KAIL  WAYS 


Single-Phase  Motors,  llie  Westin^house  Electric  <Is:  Manu- 
facturing Company  has  brought  out  a  railway  motor  adapted  to 
operate  on  single-phase  alternating-current  circuits.  This  motor 
is  very  similar  in  construction  to  the  ordinary  series-wound  oOO-volt 
direct-current  railway  motor.  It  has,  however,  more  field  poles 
than  the  ordinary  direct-current  motor;  and  the  pole  pieces  are 
laminated  to  avoid  heating  of  the  iron  l)y  eddy  currents  caused 
hv  the  influence  of  the  alternating  current.  There  are  also  other 
special  features  in  the  design  that  reduce  tlie  sparking  at  the  com- 
mutator, which  sparking  was  for  several  years  the  greatest  obstacle 
to  the  use  of  alternating-cniTcnt  motors  of  this  kind.  In  the  ^^  est- 
inghou.se  .sy.stem  thi-  cun-cnt  is  taken  from  tlie  trolley  wire  at  high 
potential,  and  is  reduced  by  an  auto-transformer  on  the  car.  This 
auto-transformer  is  connected  with  an  induction  regulator  .so  ar- 
Vanged  that  a  low  voltage  can  be  sup])lied  to  the  motor  in  .starting 
or  for  .slow  running,  and  this  voltage  increased  to  increa.se  the  speed. 
There  is  thus  no  need  to  reduce  the  trolley  voltage  by  wa.sting  part 
of  it  in  a  rheostat,  as  is  the  case  with  direct-current  motors;  and  the 
efficiency  during  acceleration  is,  therefore,  higher  with  this  alternating 
.svstem  than  witli  tlie  direct  current.  Several  other  single-pha.se 
railwav  motors  are  also  being  worked  out  at  the  present  time,  includ- 
ing that  of  the  Cleneral  Electric  Company. 

AIternatinK=Current  Motor  Advantages.  There  are  two 
great  advantati'es  secured  bv  the  u.se  of  an  alternating-current  railwaV 
motor.  The  fir.st  is  a  reduction  in  investment  and  operating  expen.ses 
by  doing  away  with  substations  containing  rotary  converters.  Such 
substations  are  necessary  on  long  lines  of  railway  operating  with 
direct-current  motors.  The  second  advantage  is  that,  owing  to  the 
fact  that  a  high  ten.sion  Ci'rrent  can  be  u.sed  on  the  trolley  wire  and 
retluced  by  a  transformer  on  the  car,  the  difficuliies  of  collecting  a 
lariie  amount  of  energv  from  a  trolley  wire  are  much  reduced. 

First,  in  regard  to  the  sub.stations,  it  will  be  seen  that  with 
the  alternating-current  motor  .system,  high-tension  current  can  be 
conducted  from  the  power  house  to  sub.stations  along  the  line  which 
contain  nothin";  but  .static  transformers.  Since  these  transformers 
have  no  revolving  parts  they  do  not  recpiire  the  constant  attendance 
that  a  rotary  converter  does.  Furthermore,  the  investment  in  rotary 
converters  is  entirely  dispen.sed  with,  and  this  makes  a  considei'al)le 


ELECTRIC    RAILWAYS  115 

reductioi:  in  the  total  cost  of  the  distribution  plant.  With  the  alter- 
nating-current system,  current  is  fed  direct  to  the  trolley  wire  from 
the  secondary  terminals  of  the  transformers  at  the  substations. 

As  regards  the  advantages  of  carrying  a  high  voltage  on  the 
trolley  wire,  it  will  readily  l)e  seen  that,  since  the  amount  of  power, 
or  the  watts  recpiired  by  a  car,  is  ecpuil  to  the  product  of  the  voltage 
and  current,  an  increase  in  the  voltage  reduces  the  volume  of  current 
necessary.  By  having  high  voltage  on  the  trolley  wire,  even  a  large 
car  can  be  operated  with  a  small  volume  of  current,  and  this  current 
can  be  taken  through  an  ordinary  trolley  wheel  without  difficulty. 
Where  500  volts  is  the  pressure  used  on  the  trolley  wire,  there  is  con- 
siderable flashing  and  burning  of  trolley  wheel  and  wire  when  large 
cars  and  locomotives  are  run,  owing  to  the  heavy  current  conducted; 
and  this  has  been  one  of  the  principal  reasons  for  the  adoption  (jf 
the  third  rail  instead  of  the  trolley  on  certain  roads.  Even  with  the 
third  rail,  the  volume  of  current  that  must  be  conducted  to  large 
electric  locomotives  involves  some  difficulties  in  the  way  of  heated 
contact  shoes  and  considerable  loss  of  energy.  The  use  of  high 
voltage  on  the  trolley  wire,  with  transformers  on  the  car  to  reduce 
the  voltage  to  a  safe  pressure  for  use  on  the  motors,  overcomes 
manv  of  the  difficulties  that  would  otherwise  be  found  in  the  use 
of  electricity  for  heavy  railroad  work. 

OPERATION. 

Power  Taken  by  Cars,  The  amount  of  power  re(juired  in 
the  practical  operation  of  a  car  depends  upon  so  many  variabk' 
ekMucuts  that  many  of  the  calculations  sometimes  given  foi-  deter- 
mining the  power  reipiired  by  a  car  are  of  littk'  value,  '^llie  theo- 
retical horsepower  recjuired  to  maintain  a  car  at  a  certain  sj>eed 
on  a  level,  is  evidently  the  tractive  effort  in  pounds  multiplied  by 
the  speed  in  feet  per  minute  and  divided  by  33,000.  What  the 
tractive  effort  per  ton  of  car  will  be,  depends  on  the  condition  of 
the  rail  and  on  several  other  imcertain  factors.  For  street-railway 
motor  cars,  20  pounds  })er  ton  is  the  usual  tractive  effort  assumed 
as  necessary.  A  calculation  of  this  kind,  iiowever,  takes  no  account 
of  the  losses  in  the  motors  and  gears,  nor  of  the  fact  that  the  greater 
part  of  the  power  rc(|iiiie(l  to  ])ropel  a  street  car  iu  practical  service 
is  used  in  accelerating  the  car  from  a  state  of  rest  to  full  speeil.     In 


116 


ELECTRIC    RAILWAYS 


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ELECTRIC    RAILWAYS  117 

interurban  service,  of  course,  the  power  required  in  acceleration  is 
not  so  great  a  proportion  of  the  whole. 

The  safest  figures  to  use  in  engineering  calculations  as  to  the 
amount  of  power  recjuired,  are  those  taken  from  actual  results  ob- 
tained in  everyday  commercial  service,  llie  })ower  required  by 
an  eight-ton  car  in  service  in  a  large  city  like  Chicago,  is  in  the  neigh- 
borhood of  one  kilowatt  hour  per  car-mile  run.  On  outlying  lines 
this  figiu'e  may  be  reduced  to  .7  kilowatt  hour,  and  in  the  down-town 
districts  may  run  uj)  to  1.5  kilowatt  hours  per  .car  mile.  Double- 
truck  cars  in  city  service,  weighing  from  20  to  25  tons,  take  from 
2j  to  4  kilowatt  hours  per  car  mile  at  the  power  station.  Interurban 
cars  around  Detroit,  weighing  about  32  tons,  in  interurban  service, 
making  25  miles  per  hour,  including  stops,  in  level  country,  and 
geared  to  43  miles  per  hour,  take  about  3  kilowatt  hours  per  car  mile 
at  the  power  station.  However,  interurban  railway  conditions  are 
extremely  variable. 

The  reports  of  several  Indiana  electric  railways  show  an  average 
powei'  consumption  of  1.48  kilowatt  hours  per  car  mile  for  city  cars 
and  5.18  kilowatt  hours  for  interurban  cars,  including  line  and  dis- 
tribution losses. 

An  interurban  car  weighing  31i  tons  and  ecjuipped  with  two 
150  horsepower  motors,  on  a  test  run  of  50  miles  at  an  average  speed 
of  39  miles  per  hour  consumed  2.20  kilowatt  hours  per  car  mile. 
This  car  made  18  stops.  A  similar  car  under  the  same  conditions 
made  the  same  run  at  an  average  speed  of  2G  miles  per  hour  with 
44  stops,  consumed  2.44-kilowatt  hours  and  a  third  car,  making  12 
stops  and  at  a  speed  of  33  miles  per  hour,  consumed  2.10  kilowatt 
hours  per  car  mile.  These  individual  car  test  figures  are  from 
measurements  taken  at  the  car  and  do  not  include  line  losses. 

Road  Tests  of  Electric  Cars.  Of  late  considerable  attentioji 
has  been  given  to  making  road  tests  of  electric  cars.  The  results 
of  the  tests  are  usually  plotted  in  the  form  shown  in  Fig.  93.  Time 
is  plotted  horizontally  in  seconds,  while  volts,  amperes,  speed  and 
per  cent  grade  are  plotted  vertically.  The  diagram  referred  to  is 
the  result  of  a  continuous  run  of  0  minutes  of  a  32.5  ton  car  ecjuipped 
with  two  motors.  The  line  voltage,  motor  consumption  and  other 
readintrs  inav  l)c  ()l)tained  for  anv  instant  of  time.  The  acceleration 
in  miles  per  hour  per  second  niay  be  ()l)taiiied  by  noting  the  increase 


118  ELECTRIC    KAIL  WAYS 

in  height  of  the  speed  curve  in  one  second.  In  making  such  a  test 
the  necessary  instruments,  vohmeters,  ammeters,  wattmeters  and 
speed  incHcators  are  mounted  direct  on  the  car  and  are  read  at  in- 
tervals of  a  few  seconds. 

■   The  curve  of  motor  consumption  gives  an  idea  of  the  abnormal 
current  required  to  get  the  car  under  headway. 

Economy  in  Power.  As  already  stated,  a  large  part  of  the 
enerffv  taken  bv  a  car  in  citv  service  is  used  in  accelerating  the  car. 
Much  of  this  energy  must  be  destroyed  or  used  up  in  the  brake  shoes 
at  the  next  stop.  The  energy  stored  up  in  a  car  by  process  of  accel- 
eration is  represented  by  the  formula: 

Mass  in  lbs.  X  (Velocity  in  ft.  per  sec.)" 
Energy  m  tt.  lbs.  = 7, ,   which 

is  the  formula  for  kinetic  or  live  energy,  the  derivation  of  which  is 
found  in  any  Instruction  Paper  on  ^Mechanics.  In  performing  any 
given  schedide  with  frequent  stops,  the  more  rapid  the  acceleration 
the  lower  the  maximum  speed  recjuired  to  make  the  schedule,  and  the 
less  the  energy  reciiiired  in  acceleration.  For  city  street  and  elevated 
service,  therefore,  rapid  ac-celeration  and  low  maximum  speeds  are 
desirable  because  not  only  more  economical  but  safer. 

For  economical  oj)eration  with  any  given  equipment  and  scheil- 
ule,  it  is  important  to  use  as  nuich  of  the  energy  stored  up  in  the 
car  as  possible,  before  wasting  it  by  applying  the  brakes.  ^Motors 
are  built  of  a  size  to  yield  the  large  horsepower  required  in  accelera- 
tion, and  consetjuently  are  lightly  loaded  when  operating  the  car 
at  maximum  speed.  To  economize  in  power,  current  should  be  shut 
off  as  soon  as  possible  after  the  car  has  attained  full  sj)eed;  and  tlic 
car  should  be  allowed  to  <lrift  without  current  as  long  as  possible 
before  the  brakes  are  applied.  In  this  way  the  energy  steered  in  the 
car  will  proj)el  it  at  nearly  maximum  speed  for  a  consideral)le  dis- 
tance between  stops;  there  will  be  the  smallest  possible  waste  of 
cnergv  in  the  brake  shoes;  and  the  losses  of  energy  which  take  place 
when  the  current  is  in  the  motors  will  l)e  prevented  as  far  as  possible. 
Practical  tests  as  well  as  theoretical  calculations  show  a  ])ossibility 
of  verv  material  saving  in  energy  in  the  operation  of  an  electric  railway 
car  or  train,  by  the  observance  of  this  simple  rule  of  drifting  as  nnich 
as  possible  and  using  the  brakes  as  little  as  possible.  AMiatever 
energv  is  used  up  in  the  brake  shoes  is  necessarily  wasted.     The 


ELECTKIC    RAILWAYS  119 

smaller  this  waste  can  be  kept  while  performing  a  given  service,  the 
greater  the  economv  secured. 

Cost  of  Power.  The  reports  of  85  per  cent  of  the  railway 
power  generating  stations  in  Indiana  show  the  average  cost  at  the 
.station  per  kilowatt  hour  to  be  .755  cent.  This  was  divided  as  follows : 
P\iel  .52()  cents,  labor  .158  cents,  lubricants  and  miscellaneous  sup- 
plies .032  cents,  repairs  .039  cents.  Tlie  lowest  cost  reported  was 
.505  cents. 

During  1901  the  average  cost  of  power  generated  at  the  power 
house  of  the  Indiana  I'nion  Traction  Company  was  .443  cents  per 
kilowatt  hour  at  the  switchboard.  Distributed  from  the  substations 
it  was  .705  cents  per  kilowatt  hour.  Natural  gas  was  used  for  fuel. 
On  occasions  when  this  failed,  coal  at  $1.50  per  ton  was  burned. 

Sliding  and  Spinning  Wheels.  In  accelerating  a  car,  how- 
ever, there  is  no  economy  in  turning  on  current  so  rapidly  as  to  spin 
the  wheels.  As  mentioned  in  the  section  on  "Brakes,"  the  tractive 
effort  between  wheels  and  rails  falls  off  about  two-thirds  when  the 
wheels  begin  to  slip;  and  this  slipping  of  wheels,  therefore,  reduces 
the  chance  of  securing  the  acceleration  which  is  possible.  For  the 
same  reason,  in  making  emergency  sto}:)s  either  by  the  use  of  brakes 
or  by  reversing  the  motors,  care  should  be  taken  not  to  slide  the 
wheels,  as  by  so  doing  the  time  required  to  stop  the  car  is  much 
increased. 

In  the  ordinary  straight  air-brake  ecpupment  used  on  heavy 
electric  cars,  there  is  much  higher  pressure  carried  in  the  storage 
reservoir  than  it  is  permissible  to  turn  into  the  brake  cylinder,  since, 
if  the  full  ])ressure  were  turned  into  the  brake  cylinder,  it  would 
result  in  sliding  of  the  wheels — which,  it  has  just  been  shown,  is 
something  to  be  avoided,  not  only  on  account  of  making  flat  spots 
on  the  wheels,  but  also  because  of  the  reduction  in  the  braking  force 
as  soon  as  the  wheels  begin  to  slide.  An  experienced  motorman 
can  tell  from  the  feeling  of  the  car  when  the  wheels  are  sliding,  and 
will  instantlv  release  the  brake  sufficientlv  to  allow  the  wheels  to  be<;in 
to  revolve  as  soon  as  he  notices  that  this  has  taken  place. 

The  friction  between  brake  shoes  and  car  wheels  decreases  as 
the  speed  increases.  A  certain  pressure  applied  to  the  brake  shoes 
upon  a  car  running  50  miles  per  hour,  therefore,  exerts  much  less 
retarding  force  than  the  same  pressure  at  ten  uiiles  pcv  hour.     In 


120 


ELECTRIC    RAILWAYS 


order  to  give  the  same  hrakiiig  or  returcling  force  at  higher  speeds, 

the  brakes  must  be  apphed  harder  than  at  the  lower  speeds.     If 

thev  are  applied  at  the  maximum  ])ressure  possible  without  sliding 

the  wheels  at  higher  speeds,  it  is  evident  that  this  pressure  must 

be  reduced  as  the  speed  of  the  car  is  reduced,  or  the  wheels  will  be 

"skidded."     In  the  Westinghouse  high-speed  automatic  air  brake 

used  on  steam   roads,  this  reduction  of  pressure  is  automatically 

accomplished. 

TESTING    FOR   FAULTS. 

Bond  Testing.  It  is  important  to  test  the  conductivity  of 
lail  l)()nds  from  time  to  time  in  order  to  determine  if  they  have  de- 
teriorated so  as  to  reduce  their  conductivity  and  introduce  an  imneces- 


©        © 


-> 


3// 


-3ff. 


Fig.  94.    Bond  Testing. 

sary  amount  of  resistance  into  the  return  circuits.  One  way  of 
doing  this  is  to  measure  the  drop  in  ])otential  over  a  bonded  joint 
as  compared  with  the  droj)  in  potential  of  an  ecpial  length  of  unbroken 
rail.  To  do  this,  an  apj)aratus  is  em])l()yed  wherein'  sinudtaneous 
contact  will  be  made  bridging  three  or  more  feet  of  rail  and  an  ecjual 
length  of  rail  including  the  bonded  joint,  as  shown  in  Fig.  1)4,  which 
illustrates  the  connections  of  a  conmion  form  of  apparatus  where 
two  milli-voltmeters  are  employed  that  measure  the  drop  in  voltage 
of  the  bonded  and  unbonded  rail  simultaneously.  If  the  current 
flowing  through  the  rail  due  to  the  operation  of  the  cars  were  con.stant, 
of  course  one  milli-voltmeter  might  l)e  used,  being  connected  first 
to  one  circuit  and  then  to  the  other.  The  current  in  the  rail,  however, 
fluctuates  rapidly,  so  that  two  instruments  are  necessary  for  rapid 
work.  The  resistance  of  the  boiKh'd  joint  is  usually  considerably 
more  tliaii  tliat-of  ti:e  unbroken  rail,  and  the  niilli-voltmeter  u.sed  to 


ELECTIUC    RAILWAYS  121 


bridge  the  joint  consequently  need  not  be  so  sensitive  as  that  bridgin^^ 
the  unbroken  rail. 

In  another  form  of  apparatus,  a  telephone  receiver  is  used  in- 
stead of  the  milli-voltmeter,  the  resistance  of  a  long  unbroken  rail 
being  ])alanced  against  that  of  the  bonded  joint,   as  in  a  Wheat-    ^ 
stone  bridge,  until,  upon  closing  the  circuit,  these  two  resistances 
A\hen  balanced  give  no  sound  in  the  telephone  receiver. 

Bond  tests  of  this  kind  can  be  made  with  satisfaction  oftly 
\-ihen  a  considerable  volume  of  current  is  flowing  through  the  rails 
at  the  time  of  the  test,  })ecause  the  drop  in  voltage  is  dependent 
(m  the  current  flowing,  and  in  any  event  is  small.  It  has  some- 
times been  found  necessary  or  advisable  to  fit  up  a  testing  car  ecjuipped 
with  a  rheostat  which  will  itself  use  a  considerable  volume  of  current, 
so  as  to  give  a  current  in  the  rail  which  will  give  an  appreciable  drop 
of  potential  across  a  bonded  joint.  Some  of  the  latest  forms  of  testing 
cars  carry  motor  generators  which  will  pass  a  large  current  of  known 
value  through  a  bonded  joint,  and  so  cause  a  drop  of  potential  across 
the  joint  large  enough  to  be  easily  measured. 

notor=Coil  Testing.  Testing  for  faults  in  the  motor  armature 
and  field  coils  is  done  in  a  great  variety  of  ways.  The  resistance 
of  these  coils  can  be  measured  by  means  of  a  Wheatstone  bridge 
employing  a  telephone  receiver  in  place  of  the  galvanometer  used 
in  such  bridges  in  laboratory  practice;  but  other  less  delicate  tests 
are  also  in  use. 

Another  method  is  to  pass  a  known  current  through  the  coil 
to  be  tested  and  to  measure  the  drop  in  the  voltage  between  the 
terminals  of  the  coil,  the  voltage  divided  by  the  current  efjualing 
the  resistance. 

A  simple  method,  and  (me  which  involves  no  delicate  instru- 
ments, has  lately  been  introduced  into  railway  shop  practice  very 
successfully.  This  is  known  as  the  tranfiformer  test  for  short-circuited 
coils.  It  requires  an  alternating  current  which  can  easily  be  supplied 
either  by  a  regular  motor  generator  or  by  putting  collecting  rings 
onto  an  ordinary  direct-current  motor  and  connecting  these  rings  to 
bars  of  opposite  polarity  on  the  commutator. 

The  method  of  testing  for  short-circuited  armature  coils  em- 
ployed in  the  shops  of  the  St.  Louis  Transit  Company  is  indicated 
in  diagram  in  Fig.  95.     A  core  built  up  of  soft  laminated  iron  is 


\22 


ELECTKIC    KAILWAVS 


wound  with  2S  turns  of  No.  (>  copper  wiic.  This  coil  is  supphed 
with  alternatini>;  current  from  a  llO-voU  circuit.  The  core  has 
jiolc  pieces  made  to  ht  the  surface  of  tiie  armature.  ^Vhen  {)ne 
side  of  a  short-circuited  coil  in  the  arinatuie  is  hroufi^ht  l)etween 
the  pole  pieces  of  this  testin<^  transformer,  as  in  Fig.  Oo,  the  short- 
circuited  armature  coil  becomes  like  the  short-circuited  secondary 
of  a  transformer,  and  a  laro;e  current  will  flow  m  it.  This  current 
will  in  time  manifest  itself  bv  heatiufj  the  coil;  but  it  is  not  nece.s.sarv 
to  wait  for  this,  as  a  piece  of  iron  held  over  that  .side  of  the  coil  not 
enclo.sed  between  the  pole  pieces,  as  indicated  in  Fi<i;.  il."),  will  be 

\25-cyc/e,  wo  vo/f 
A.  C.  supp/y 

28  furns  No.  6  w/re 

Laminated     core 


Short  c/rcu/fed 

CO// 


Po/nt  of 
attract/on 
of  piece  of 
irorj 


Fig.  9.^.    Method  of  TestiiiK  for  Short-circuited  Arinat  are  Coils. 


attracted  to  the  face  of  the  armature  if  held  directly  over  tlie  coil. 
but  will  be  attracted  at  no  other  j)oint. 

This  testing  can  be  done  very  rapidly,  and  does  not  recjuire 
delicate  instruments  or  skilled  operators. 

Te.sts  for  short  circuits  in  field  coils  can  be  made  in  a  similar 
manner,  by  placing  the  coils  on  a  core  which  is  magnetized  by  alter- 
nating current.  'I'lic  presence  of  a  .short  circuit,  even  of  one  con- 
volution of  a  field  coil,  will  be  apparent  from  the  increase  in  the 
alternating  current  recjuired  to  magnetize  the  core  upon  which 
the  field  coil  is  being  te.sted. 


ELECTRIC    RAILWAYS  123 

The  insulation  resistance  of  armatures  and  fields  is  frequently 
tested  by  means  of  alternating  current,  about  2,000  volts  being 
the  connnon  testing  voltage  for  oOO-volt  motor  coils.  One  termi- 
nal of  the  testing  circuit  is  connected  to  the  frame  of  the  motor, 
and  the  other  to  its  windings.  Any  weakness  in  the  insulation 
insufficient  to  withstand  2,000  volts  will^  of  course,  be  broken  down 
by  this  test.  xAlternating  ciu'rent  is  generally  used  for  such  tests 
because  it  is  usually  more  easily  obtained  at  the  proper  voltage,  as 
it  is  a  simple  matter  to  put  in  an  alternating  transformer  which  will 
give  any  desired  voltage  and  which  can  be  controlled  by  a  primary 
circuit  of  low  voltage. 

Open  circuits  in  the  armature  can  be  easily  detected  by  placing 
the  armatiu'e  in  a  frame  so  that  it  can  })e  rotated,  the  frame  being 
provided  with  brushes  resting  90°  apart  on  the  commutator.  If 
either  an  alternating  or  direct  current  be  passed  through  the  armature 
by  means  of  these  brushes,  and  the  armature  be  rotated  by  hand, 
a  flash  will  occur  when  the  open-circuited  coils  pass  under  the  brushes. 
A  large  current  should  be  used. 

The  tests  just  mentioned  are  among  the  best  of  the  methods 
used  by  electric-railway  companies  for  systematic  work  in  the  loca- 
tion of  certain  classes  of  faults.  A  large  number  of  other  methods 
of  testing  have  also  been  evolved. 

The  following  are  some  of  the  most  common  faults  exy)erienced 
with  electric  railway  car  equipments: 

Grounds.  As  one  side  of  the  circuit  is  grounded,  any  acci- 
dental leakage  of  current  from  the  car  wiring  or  the  motors  to  ground 
will  cause  a  partial  short  circuit.  Such  a  ground  on  a  motor  will 
manifest  itself  by  Ijlowing  the  fuse  or  opening  the  circuit  breaker 
whenever  current  is  turned  into  the  motor^  In  case  the  fuse  ])lows 
when  the  trolley  is  placed  on  the  wire  and  the  controller  is  off,  it  is 
a  sign  that  there  is  a  ground  somewhere  in  the  car  wiring  outside 
of  the  motors.  ^Moisture  and  the  abrasion  of  wires  are  the  most 
common  causes  of  grounds  in  car  wiring.  In  motors,  defects  are 
usually  due  to  overheating  and  the  charring  of  the  insulation. 

Burn-Outs.  Burning  out  of  motors  is  due  to  two  ireneral 
causes:  First,  a  ground  on  the  motor,  which,  by  causing  a  partial 
short  circuit,  causes  an  excessive  current  to  flow;  second,  overload- 


124 


ELFX'TRIC    liATLWAYS 


ing  the  motor,  Avhic-h  causes  a  gradual  l)uniing  or  carbonizing  of 
the  insulation  until  it  finally  breaks  down. 

Short-circuited  field  coils  having  a  few  of  their  turns  short- 
circuited,  if  not  proni})tly  discovered,  are  likely  to  result  in  hurned- 
out  armatures,  as  the  weakening  of  the  field  reduces  the  counter- 
electromotive  force  of  the  motor,  so  that  an  abnormally  large  current 
flows  through  the  armatures.  Cars  with  partially  short-circuited 
fields  are  likely  to  run  above  their  proper  speed,  though,  if  only  one 
motor  on  a  four-motor  equipment  has  defective  fiekls,  the  motor 
armature  is  Hkely  to  burn  out  before  the  defect  is  noticed  from  the 
increase  in  speed.  .  • 

Defects  of  Armature  Windings.  Defects  in  armature  wind- 
ings probably  cause  one- 
third  the  maintenance  ex- 
penses of  electrical  ecjuip- 
ment  of  cars.  Almost  all 
repair  shops  have  men  con- 
tinually employed  in  re})air- 
ing  them.  Tiie  most  fre- 
quent trouble  with  arma- 
tures is  through  failnre  of 
the  insulation  of  the  coils 
and  consequent  "ground- 
ing." 'J'his  term  is  nsetl  in 
connection  with  armatures 
and  fields  and  other  elec- 
trical apparatus  where  a 
direct  path  exists  to  ground. 
As  the  armature  core  is  electricallv  connected  to  the  ground  through 
its  bearings  and  the  motor  casing,  a  break  down  of  the  insulation 
of  the  coils  in  the  slots  permits  the  current  to  pass  directly  to  ground. 
This  diunts  the  current  around  the  fields  aiid  an  abnormal  current 
flows  l)ecause  of  their  weakness.  The  circuit  breaker  or  fuse  is 
placed  in  circuit  to  protect  the  apparatus  in  such  an  emergency,  but 
usually  before  such  devices  break  the  circuit,  several  of  the  coils  of 
the  armature  are  burned  in  such  a  manner  as  to  make  their  removal 
necessary.     The  coils  are  so  wound  on  top  of  one  another  that  in 


Fig.  9r>, 


ELECTRIC    RAILWAYS 


121 


Fig.  97 


order  to  replace  one  coil  alone,  one-fourth  of  the  coils  of  the  arma- 
ture must  be  lifted. 

With  the  armature  of 
No.  1  motor  grounded  the 
car  will  not  operate  and  if 
the  resistance  points  he 
passed  over,  the  fuse  will 
usually  blow.  When  No.  2 
motor  is  grounded  the  action 
of  No.  1  motor  is  not  im- 
paired and  this  latter  motor 
will  pull  the  car  until  the 
controller  is  thrown  to  the 
multiple  position.  But  if 
the  motors  are  thrown  in 
multiple,  the  path  through 
the  ground  of  No.  2  motor 
shunts  motor  No.   1.     A, 

study  of  Fig.  IS  will  make  this  evident. 

Next  to  grounding,  open  circuits  are  the  most  serious  defects 

of   armatiu'es.      These   are 

usuallv   caused  bv  burning 

in  two  of  the  wires  in  the 

slot,    or   where    they    cross 

one    another   in    passing  to 

the  commutator.     Some- 
times the  connections  where 

the   leads    are    soldered   to 

the    commutator   become 

loose. 

The   effect    of    an    open 

circuit  is  shown  in  Fig.  9(). 

The   circuit  is  open  at    n. 

The    brushes   are   on    seg- 
ments a  and  d.    By  tracing 

out  the  winding  it  will  be 

found  that  no  current  flows  through  the  wires  marked  in  heavy  lines. 

Whenever  segments  c  and  d  are  under  a  brush  the  coil  with  the  open 


Fig.  98. 


126 


ELECTRIC    RAILWAYS 


circuit  is  bridtfcd  by  the  brush  and  current  flows  as  in  a  normal 
armature.  As  segment  c  passes  out  from  under  tlie  Imish  the  open 
circuit  interrupts  the  current  in  half  the  armature  and  a  long  flaming 
arc  is  drawn  out. 

In  Fig.  07  is  shov\n  the  result  of  a  short  circuit  between  two 
coils.  The  short  circuit  is  at  h,  c,  the  two  leads  coming  in  contact 
with  each  other  when  they  cross.  The  efi'ect  is  to  short-circuit  all 
of  the  winding  indicated  by  the  heavy  lines. 

Mistakes  in  Winding  Armatures.  The  armature  winder  is 
given  very  simple  rules  as  to  how  to  wind  the  arma'ture,  but  the  great 
number  of  leads  each  to  be  connected  to  their  proper  commutator 
segment  sometimes  so  confuse  him  that  misconnections  are  made. 
The  efl'ect  of  getting  two  leads  crossed  is  shown  in  Fig.  98.     The 

leads  to  segments  /;  and  c 
from  the  right  are  shown 
interchanged  This  short- 
circuits  the  coils  shown  in 
heavy  lines.  The  abnormal 
current  resulting  in  these 
would  iisuallv  cause  them 
to  burn  out. 

Fig.  00  shows  the  results 
of  placing  all  of  the  top 
leads  or  all  of  the  bottom 
leads  one  segment  beyond 
the  proper  position.  This 
causes  the  circuit  starting 
from  a  and  traveling  coun- 
ter clockwise  aroimd  the 
armature  to  return  on  segment  m  instead  of  on  segment  h  as  is  the 
case  in  Fig. 


Fig.  99. 


97. 


The  only  result  of  such  connections  is  to  change  the  direction 
of  rotation  of  the  armature.  It  may  be  noticed  by  comparing  the 
two  figures  that  with  the  positive  brush  on  segments  a  the  arrows 
show  the  currents  to  be  in  opposite  directions  in  coils  similarly  located 
with  reference  to  the  position  of  the  brushes  Some  armatures  are 
intended  to  be  wound  as  in  the  last  case  mentioned. 


ELECTKIC    RAILWAYS 


127 


Sparking  at  the  Commutator.  As  railway  motors  are  made 
to  operate,  and  usually  do  oj)erate,  almost  sparklessly,  sparking  at  the 
brushes  may  be  taken  as  a  sign  that  something  is  radically  wrong. 

The  pressure  exerted  by  the  spring  in  the  brush  holder  may 
not  hold  the  brush  firmly  against  the  conmiutator. 

If  brushes  are  burned  or  broken  so  that  they  do  not  make  good 
contact  on  the  commutator,  they  should  be  renewed  or  should  be 
sandpapered  to  fit  the  commutator. 

A  dirty  commutator  will  cause  sparking. 

A  commutator  having  uneven  surface  will  cause  sparking,  and 
should  be  polished  off  or  turned  down. 

Sometimes  the  mica  segments  between  commutator  bars  do  not 
wear  as  fast  as  the  bars 
and  when  this  is  the  case, 
the  brushes  will  be  kept 
from  making  good  contact 
when  the  commutator  bars 
are  slightly  worn.  .  The 
remedy  is  to  take  the  arm- 
ature into  the  shop,  and 
groove  out  the  mica  between 
the  commutator  bars  for  a 
depth  of  about  ^^j-inch  be- 
low the  commutator  surface. 

A  greenish  flash  which 
appears  to  run  around  the 
commutator,     accompanied  pig.  loo. 

by  scoring  or  burning  of  the 

commutator  at  two  points,  indicates  that  there  is  an  open-circuited 
coil  at  the  points  at  which  the  scoring  occurs  as  in  Fig.  100. 

The  magnetic  field  may  be  weakened  by  a  short  circuit  in  the 
field  coils,  as  before  explained,  and  this  may  give  rise  to  sparking. 

Short  circuits  in  the  armature  may  give  rise  to  sparking,  but 
will  also  be  made  evident  by  the  jerking  motion  of  the  car  and  the 
blowing  out  of  the  fuse. 

Failure  of  Car  to  Start.  The  failure  of  the  car  to  start 
when  the  controller  is  turned  on  may  be  due  to  any  of  the  following 
causes : 


128  ELECTRIC    RAILWAYS 

Opening  of  the  circuit  breaker  at  the  power  house: 

Poor  contact  between  the  wheels  and  the  rails  owing  to  dirt  or 
to  a  breaking  of  the  l)ond  wire  (vnnections  l)etween  the  rail  on  which 
the  car  is  standing  and  the  adjacent  track. 

One  controller  may  be  defective  in  that  one  of  the  contact  fingers 
may  not  make  connection  with  the  drum.  In  this  case  try  the  other 
controller  if  there  is  another  one  on  the  car. 

The  fuse  may  be  blown  or  the  circuit  breaker  opened.  The 
occurrence  of  either  of  these,  however,  is  usually  accompanied  by 
a  report  which  leaves  little  doubt  as  to  the  cause  of  the  interruption 
in  current. 

The  lamp  circuit  is  always  at  hand  for  testing  the  presence  of 
current  on  the  trolley  wire  or  third  rail.  If  the  lamps  light  when 
the  lamp  circuit  is  turned  on,  it  is  a  tolerably  sure  sign  that  any 
defect  is  somewhere  in  the  controllers,  motors,  or  fuse  boxes,  although 
in  case  the  cars  are  on  a  very  dirty  rail  enough  current  might  leak 
through  the  dirt  to  light  the  lamps,  but  not  sufficient  to  operate  the 
cars.  In  such  a  case,  the  lamps  will  immediately  go  out  as  soon  as 
the  controller  is  turned  on.  Ice  on  the  trolley  wire  or  third  rail  will 
have  the  .same  efli'ect  as  dirt  on  the  tracks. 

LOCATING  DEFECTS  IN  MOTOR  AND  CONTROLLER 

WIRING. 

Defects  in  the  wirings  are  those  due  to  (1)  open  circuits,  (2) 
sliort  circuits.  Open  circuits  make  themselves  evident  by  no  flow 
of  current,  short  circuits  usually  by  a  blowing  of  the  fuse  or  opening 
of  the  breaker.  The  point  of  the  short  circuit  or  "ground"  can  be 
located  roughly  by  noting  on  what  point  the  fuse  is  blown.  Accurate 
location  can  be  made  by  cutting  out  the  motors,  disconnecting,  otc, 
according  to  directions  in  the  following  pages.  The  tests  outlined 
apply  particularly  to  the  K  type  of  controller  with  two-motor  equip- 
ment. 

OPEN=CIRCUIT  TESTS. 

No  current: 

On  1st  point, 

Open  circuit  but  not  located. 
On  1st  point  multiple, 

Motors  most  probably  O.  K. 


ELECTRIC    KAILWAYS  12U 


On  series-resistance  points  after  trying  1st  point  multiple, 
Open  circuit  outside  controller  and  equipment  wiring. 

^Yith  an  open  anywhere  between  trolley  and  ground  no  current 
will  flow  on  the  first  point.  Opens  are  most  likely  to  occur  in  the 
motors  and  these  may  be  tested  first.  However,  as  will  be  explained 
later,  one  open  in  an  armature  will  not  stop  the  current.  To  test 
the  motors  open  the  breaker  and  put  the  controller  on  the  first  point 
multiple.  Then  flash  the  l)reaker  cjuickly.  Current  flowing  indi- 
cates that  one  or  the  other  of  the  motors  has  an  open  circuit.  In 
the  series  position  this  open  prevented  the  flow  but  in  multiple  the 
current  flows  through  the  other  motor.  "Which  one  is  at  fault  can 
be  quickly  determined  by  returning  the  controller  to  the  off  position 
and  cutting  out  one  or  the  other  of  the  motors  by  means  of  the  cut-out 
switch  and  then  trying  for  current.  The  car  can  in  any  event  be 
run  on  the  remaining  motor.  On  returning  to  the  shop  the  open 
can  be  determinetl  definitely  by  the  use  of  the  lamp  bank. 

But  should  no  cm-rent  flow  when  the  l)reaker  is  flashed  on  the 
6th  point  it  is  reasonable  to  presume  that  the  motors  are  O.  K.  and 
that  the  open  is  elsewhere.  The  ground  for  such  a  supposition  is 
that  as  there  is  a  path  through  each  motor  normally,  there  would 
necessarily  be  an  open  in  each  one  to  stop  the  current.  It  is  hardly 
probable  that  such  a  coincidence  would  occur. 

After  failure  to  find  fault  with  the  motors,  doubt  as  to  the  resist- 
ance may  be  removed.  The  controller  should  be  placed  on  progres- 
sive series-resistance  points  and  the  breaker  flashed  on  each  one.  If 
current  is  obtained  on  any  point,  the  open  is  in  the  resistance  or  the 
resistance  lead  just  behind  the  one  being  used.  Special  care  should 
be  used  to  flash  the  breaker  quickly  for  otherwise  the  fuse  may  be 

blown. 

The  tests  indicated  are  sufficient  for  the  motors,  controllers  and 
resistance  wiring.  If  no  current  is  obtained  on  either  of  them,  the 
trouble  is  evidently  caused  by  a  bad  rail  contact,  ground  wire  oflF  if 
both  motors  are  grounded  through  the  same  wire,  an  open  in  the 
blow-out  coil,  at  the  lightning  arrester,  circuit  breaker  or  on  top  of 
the  car. 

None  of  .the  tests  applied  locate  the  open  definitely,  but  this  can 
easily  be  done  in  the  shop  or  wherever  a  lamp  bank  is  at  hand.  Con- 
nect one  terminal  of  the  lamp  bank  to  the  trolley   just  behind  the 


130  ELECTRIC    RAILWAYS 


circuit  breaker  and  the  controller  on  the  1st  point  series,  then  with 
the  other  terminal  bej^in  at  <:;r()un(l  and  trace  backwards  up  the  circuit 
luitil  the  lamps  fail  to  light.  The  path  in  a  K  type  of  controller  is 
readily  traced  with  the  help  of  Fig.  22. 

SHORT=CIRCUIT  TESTS. 

The  location  of  short-circuits  is  much  more  tedious.  The 
blowing  of  the  fuse  or  opening  of  the  breaker  will  locate  them  as 
shown  below.  The  separate  tests  can  then  be  followed  until  loca- 
tion is  definite. 

These  tests  it  must  be  kept  in  mind  are  m5re  especially  adapted 
to  cases  on  the  road  or  where  no  facilities  for  testing  are  at  hand. 

Rather  than  blow  fuses  as  frequently  as  indicated  it  would  in 
most  cases  be  better  to  place  a  lamp  bank  across  the  open  circuit 
breaker  and  note  the  flow  of  the  current  by  the  lights. 

Fuse  Blows : 

I.     When  overiiead  is  thrown  on  may  be  due  to: 

1.  ( J  rounded  controller  blow-out  coil. 

2.  Grounded  trolley  wire  or  cable.. 
8.     (1  rounded  lightning  arrester. 

II.     On  first  point: 

1.  Ci rounded  resistance  near  R  1. 

2.  Grounded  controller  cylinder. 

3.  Bridging  between  the  insulated  sections  of  cylinder. 

III.  Near  last  point  series: 

1.  Grounded  resistance  near  R  3,  R  4  and  R  5. 

2.  No.  1  motor  groimded. 

IV.  Near  last  point  multiple: 

1.  No.  2  motor  grounded. 

2.  Bridging  between  lower  sections  of  cylinder, 

3.  Armature  defective. 

CASE  I. 

Fuse  Blows  when  oyerhead  is  thrown  on: 

1.  (jrounded  controller  blow-out  coil. 

2.  Grounded  trolley  wire  or  cable. 

3.  (irounded  lightning  arrester. 

Tlie  blowing  of  the  fu.se  immediately  on  closing  the  overhead 
switch  or  circuit  breaker,  when  the  controller  is  on  tlic  off  position, 


ELECTRIC    RAILWAYS 


131 


indicates  that  the  fault  exists  somewhere  between  the  overhead  and 
the  upper  or  trolley  finger  of  the  controller. 

Should  the  defect  occur  during  a  thunderstorm,  it  may  be  pre- 
sumed at  once  that  lightning  has  grounded  the  blow-out  coil  of  the 
controller. 

CASE  II. 

Fuse  Blows  on  first  point: 

1.  Grounded  resistance  near  R  1. 

2.  Grounded  controller  cylinder. 

3.  Bridging  between  sections  of  cylinder. 

When  the  controller  is  on  the  first  point  all  of  the  wiring  of  the 
system  with  the  exception  of  the  ground  wire  for  No.  1  motor  is  con- 
nected with  trolley.  But  a  defect  in  the  wiring  beyond  the  resistance 
will  not  show  itself  on  the  first  point  by  an  abnormal  rush  of  current 


Fig.  101. 


Fig.  102. 


because  the  resistance  of  the  rheostats  is  sufficient  to  prevent  any 
excessive  flow  of  current. 

The  resistance  and  leads  and  the  contj-oller  cylinder  are  the  only 
parts  to  be  tested  when  the  fuse  blows  on  the  1st  point. 

CASE  III. 

Fuse  Blows  on  3rd  or  4th  point: 

1.  Groimded  resistance  near  II  4  or  11  5. 

2.  No  1  motor  grounded. 

With  either  of  the  above  defects  the  car  will  most  probably 
refuse  to  move  as  the  current  is  led  to  ground  before  passing  through 
the  motors. 


132 


ELECTKIC    KAIL  WAYS 


Nor c-  Dotted   lines  ~sho>v 
•Sky/ighfs. 
Atl  partitions  are  of  ^itrifiea  tile. 


Fig.  ion.    Plan  of  Car  Shop. 


ELECTRIC    RAILWAYS  133 


No.  1  motor  may  be  tested  by  cutting  it  out  of  service  by  means 
of  its  cut-out  switch.  If  this  removes  the  ground,  the  motor  is  at 
fault. 

CASE  IV. 

Fuse  Blows  near  last  point  multiple: 

1.  No.  2  motor  grounded. 

2.  Either  armature  short-circuited. 

Tlie  fact  that  the  fuse  did  not  blow  on  the  series  positions  excludes 
the  resistances  and  No.   1  motor  from   investigations  for  grounds. 

Cut  out  both  motors.  If  the  ground  still  exists  the  controller  is 
defective  If  not,  the  fault  mav  be  located  in  either  one  of  the  motors 
by  cutting  out  first  one  and  then  the  other. 

ARflATURE  TESTS  FOR  GROUNDS. 

^Yith  a  lamp  bank  at  hand  tests  for  groimded  armature  can  be 

made  as  follows: 

Throw  the  reverse  on  center.  Attach  one  terminal  of  the  lamp  bank 
to  the  trolley.  Put  the  other  tenniual  on  the  commutator  of  the  armature 
to  be  tested.  No  current  shows  the  armature  O.  K.  If  current  flows 
remove  brushes  and  try  agaiu,  to  be  certain  that  the  ground  is  not  iu  the 
leads. 

FIELD  TESTS  FOR  GROUNDS. 

Disconnect  field  leads  and  put  test  point  of  the  lamp  bank  on 

one   side  of  the  terminals.     No   current   indicates   that   the   fields 

are  O.  K. 

REVERSED  FIELDS. 

In  placing  new  fields  in  the  shell  it  often  happens  that  one  or 
more  are  wrongly  connected.  Reversed  fields  make  themselves 
known  by  excessive  sparking  at  the  brushes  in  each  case. 

In  Fig.  101  all  of  the  fields  are  connected  correctly.  The  flow 
of  magnetism  is  in  one  pole  and  out  of  the  adjacent  one.  Some  of 
the  magnetism  leaks  out  of  the  shell  and  affects  a  compass  held  near 
the  outside.  The  direction  taken  by  the  compass  needle  in  the  dif- 
ferent positions  is  shown  The  needle  should  point  in  opposite 
directions  over  adjacent  coils  and  should  lie  parallel  to  the  shell  in 
positions  half  way  between  two  coils. 

Figure  102  shows  the  flow  of  magnetism  when  one  field  is  re- 
versed. In  such  a  case  the  compass  will  take  the  position  shown. 
The  fiekl  marked  "X"  is  the  one  reversed. 

With  one  reversed  field  a  machine  will  usually  operate,  as  the 


134  ELECTRIC    RAILWAYS 

magnetisiii  in  three  of  the  poles  is  in  the  normal  (hrection.  Bnt  an 
excessive  flow  of  current  that  has  no  eftect  in  turning  the  armature 
will  take  place  on  that  side  of  the  armature  next  to  the  reversed  field. 

CAR  REPAIR  SHOPS. 

Every  electric  railway  system  has  a  repair  shop  in  which  the 
cars  are  overhauled.  Hardly  two  shops  are  built  alike.  In  those 
shops  where  only  a  few  cars  are  cared  for,  the  work  is  sometimes  all 
done  in  one  room.  The  shop  plan  shown  in  Fig.  103  was  presented 
to  the  American  Railwav  Mechanical  and  Electrical  Association  hv 
W.  D.  Wright.  It  contains  the  idea  upon  which  the  larger  shops 
are  now  being  constructed,  having  a  transfer  table  between  the 
separate  departments  on  either  side.  In  the  general  design  of  shops 
the  blacksmith  shop,  machine  shop  and  truck  shop  or  ecjuipping  shop 
should  be  close  together  as  a  great  deal  of  heavy  material  is  carried 
between  these  departments.  The  paint  shop  should  be  separated 
as  much  as  possible  from  the  other  departments  in  order  that  flying 
dust  and  dirt  be  avoided.  The  wood  shop  may  occupy  a  position  at 
a  considerable  distance  from  the  other  departments  as  no  heavy 
material  is  carried  from  this  shop  to  them. 

The  tracks  of  the  motor  and  truck  repair  shop  are  usually  pro- 
vided with  pits  so  that  trucks  and  electrical  ecjuipment  may  l>e  re- 
])aired  and  inspectetl  from  below.  The  tracks  in  shops  are  usually 
about  15  or  16  feet  between  centers.  This  gives  a  clearance  of  about 
6  or  8  feet  between  cars  when  adjacent  tracks  are  occupied. 

A  large  portion  of  the  work  done  in  the  average  shop  consists 
of  the  repairing  of  trucks  and  the  motors  mounted  on  them.  With 
the  smaller  car,  especially  those  with  single  trucks,  much  of  this 
work  is  done  from  the  pit  below  while  the  trucks  are  in  position  under 
the  cars.  In  this  case  the  armatures  are  either  removed  by  letting 
them  down  with  the  lower  half  of  the  motor  shell  by  means  of  a  pit 
jack,  or  the  lower  half  of  the  armature  shell  is  swung  down  by  the 
use  of  a  chain  and  block  placed  in  the  car  and  the  armature  rolled 
out  on  a  board. 

The  trucks  of  double  truck  cars  are  usually  taken  out  from  under 
the  car  body  when  repairs  are  to  be  made.  In  this  case  the  motor 
leads,  the  sand  box  connections  and  the  brake  rigging  are  disconnected 
and  the  car  bodv  either  raised  or  the  tiiicks  lowered  from  it.     Several 


ELECTRIC    RAILWAYS  135 

metliods  of  raising  the  car  body  are  in  use.  Where  no  special  ap- 
paratus is  at  hand,  this  is  done  by  means  of  jacks,  hych-aulic  or  me- 
chanical, placed  untler  the  side  sills  of  the  car  near  the  end  to  be 
raised.  Sometimes  an  overhead  crane  is  employed  to  lift  the  car 
body.  A  special  apparatus  to  raise  the  body  is  employed  by  the  St. 
Louis  Transit  Company.  This  consists  of  four  screw  jacks  located 
below  the  floor  of  the  shop.  An  I-beam. extends  over  the  tops  of 
the  two  located  on  the  same  side  of  the  car.  The  jacks  are  motor 
driven  by  means  of  one  sprocket  chain  so  that  they  rise  at  the  same 
speed.  When  a  car  is  to  be  raised  it  is  run  on  the  track  between  the 
jacVs,  bars  are  placed  under  the  car  resting  across  the  I-beams  and 
the  jacks  raise  the  car  off  the  trucks.  The  trucks  are  then  rolled 
out  from  under  the  car  and  the  repairs  made. 

Sometimes,  as  has  been  stated,  the  trucks  are  dropped  from  the 
car  body.  In  this  case  the  car  is  so  placed  that  the  truck  rests  on  an 
elevator  or  section  of  track  that  drops  to  the  floor  below.  After  the 
car  is  blocked  up  the  trucks  are-dropped  and  the  repairs  made.  This 
method  is  also  used  in  changing  wheels  in  small  shops.  The  old 
pair  of  wheels  is  dropped  by  a  hand-operated  drop  section  of  track. 
A  new  pair  is  then  elevated  into  position.  This  saves  jacking  up 
one  end  of  the  car. 


THE  SINQLE=PHASE  ELECTRIC  RAILWAY. 


In  110  other  lino  of  electrical  activity  have  developments  durinfif 
the  last  few  years  been  so  rapid  as  in  that  of  electric  railway  work, 
and  from  all  indications  the  limit  has  not  yet  been  reached. 

Until  recent  years  all  electric  traction  has  been  dependent  upon 
direct  current  as  a  motive  power.  This  is  due  principally  to  the 
fact  that  the  series  direct-current  motor  is  admirably  adapted  for 
such  work,  and  no  alternating-current  motor  had  been  developed 
which  could  be  substituted  for  it.  One  of  the  great  advantages 
possessed  by  the  direct-current  series  motor  is  its  large  starting 
torque,  which  may  be  several  times  greater  than  that  required  to 
propel  a  car  at  full  speed.  This  type  of  motor  is  also  essentially 
a  variable  speed  machine,  and  lends  itself  very  well  to  wide  varia- 
tions in  speed  control;  consequently,  for  many  years,  in  this  coun- 
try at  least,  all  advance  was  made  along  direct-current  lines. 

The  trolley  voltage  used  at  first  was  from  450  to  500  volts, 
this  being  supplied  directly  to  the  cars  by  means  of  a  trolley  wire, 
the  rails  being  used  for  the  return  circuit.  It  is  evident  from  the 
outset  that  the  comparatively  low  voltage,  necessitating  as  it  did  a 
correspondingly  large  current  for  a  given  amount  of  power,  would 
place  a  definite  limitation  on  the  use  of  such  a  system  for  anything 
other  than  purely  local  distribution.  To  overcome  this  difficulty 
as  far  as  possible,  the  trolley  voltage  was  gradually  raised  to  600 
or  650.  This  of  course  decreased  the  required  current,  thus  increas- 
ing the  scope  of  the  system  accordingly.  The  limit  of  increase  of 
direct-current  voltage  on  the  trolley  was  reached  at  about  this  point, 
and  the  fact  was  recognized  that  some  means  must  be  devised  for 
using  a  still  higher  voltage,  since  there  are  difficulties  to  increas- 
ing the  trolley  voltage  beyond  600  or  700,  due  to  flashing  of  the 
motors,  which  seems  to  increase  directly  with  the  voltage. 

It  may  be  mentioned  in  passing  that  one  prominent  electric 
traction  expert  has  stated  that  a  direct-current  trolley  voltage  of 
1500  can  be  used,  but  it  remains  to  be  proven  whether  or  not  he 
is  correct. 


138  THE  SINGLE-PHASE  ELE(TRI(^  RAILWAY 

A  v(>ry  satisfactory  solution  of  the  prol)lcm  for  large  city  street 
railway  systems  and  long  interurhan  roads,  consists  in  the  use  of 
a  combination  alternating-current  direct-current  system  in  which 
three-phase  high  tension  alternating  current  is  generated  and  distril)- 
uted  on  high  tension  lines  to  substations  along  the  road.  It  is  here  stepped 
<l()wn  by  means  of  transformers,  and  then  changed  to  direct  current 
by  rotary  converters,  and  supplied  to  the  trolley  wire  as  direct  cur- 
rent at  the  usual  voltage  of  say  GOO.  This  system  has  many  advan- 
tages, as  there  is  but  small  loss  in  the  high-tension  lines,  and  these 
lines  can  be  made  comparatively  small,  thus  effecting  a  consider- 
able saving   in   investment  for  copper. 

The  above  mentioned  system  of  distribution  is  very  generally 
used,  and  has  been  found  quite  satisfactory.  The  substations  can 
be  located  at  frequent  intervals,  and  the  distance  that  the  bOO-volt 
current  must  be  conducted  to  supply  the  cars  is  not  great.  By 
this  means  current  can  be  distributed  over  wide  areas  with  a  small 
loss,  where  it  would  be  impossible  to  use  the  straight  direct-current 
system  of  distribution. 

While,  as  stated,  this  furnishes  a  fairly  satisfactory  solution 
of  the  problem,  it  is  far  from  perfect,  as  it  necessitates  the  inter- 
vention of  the  rotary  converter  substation,  in  which  the  investment 
must  be  large;  and  moreover  the  cost  of  operation  is  high,  as  such 
a  station  recjuires  skilled  attendance  on  account  of  the  somewhat 
intricate  nature  of  the  rotary  converter.  The  ideal  system,  there- 
fore, is  one  which  does  away  altogether  with  the  use  of  direct  cur- 
rent, the  power  being  generated,  distributed,  and  utilized  by  the 
motors,  as  alternating  current. 

Three-phase  induction  motors  have  been  used  quite  extensively 
and  with  considerable  success  in  Europe  for  many  years  past.  The 
three-phase  motor,  however,  is  not  entirely  adapted  for  railway 
work,  since  it  possesses  the  characteristics  of  the  shunt  rather  than 
of  the  series  motor,  being  a  constant  speed,  not  a  variable  speed 
machine.  Moreover,  two  trolley  wires  are  necessary  instead  of 
one,  and  still  another  disadvantage  consists  in  the  low  power-factor 
of  the  three-phase  induction  motor  at  starting. 

The  recent  application  of  the  single-phase  alternating  current 
to  railway  work  has  opened  up  a  new  field,  which  bids  fair  to  sup- 
plant all  other  forms  of  distribution  to  a  great  extent  at  least,  and 


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THE  SIXGI.E-PIIASE  ELECTRIC  RAILWAY 


18'.) 


it  is  impossible  to  predict  at  the  present  time  just  wliat  its  limitations 
may  or  may  not  prove  to  be.  This  has  been  made  possible  by  the 
development  of  a  practical  commercial  sinujle-phase  motor,  which 
{)ermits  of  the  use  of  alternating  current  on  the  trolley  wire  with 
all  its  advantages,  and  yet  sacrifices  few,  if  any,  of  tiie  advantages 
of  the  direct-current  series  motor  on  the  car. 

This  motor,  which  is  the  latest  and  most  important  develop- 
ment in  the  electric  railway  field,  is  of  the  series  commutator  type, 


Compensating  Alternating-Current  Railway  Motor. 

and  does  not  ditter  in  principle  from  its  direct-current  contemporary. 
It  is  called  the  commutator  type  single-phase  motor,  and  is  the  one 
type  of  alternating-current  motor  which  has  the  same  desirable 
characteristics  for  railway  work  as  the  direct-current  series  motor. 
At  first  thought  it  may  seem  strange  that  a  motor  built  fun- 
damentally on  the  same  lines  as  a  direct-current  machine  would 
operate  on  an  alternating  current,  as  it  might  appear  that  the  motor 
would  tend  to  turn  first  in  one  direction  and  then  in  the  opposite 
direction  with  no  resultant  motion.  This,  however,  is  not  the  case, 
because  the  direction  of  rotation  of  a  motor  depends  upon  the  rela- 
tive direction  of  its  field  and  armature  currents.  If  now  the  field 
were  maintained  in  a  constant  direction  and  the  armature  supplied 
with  alternating  current,  then  the  tendency  would  be  to  rotate  first 
in  one  direction  and  then  in  the  other,  it  is  true,  but  as  a  matter  of 
fact  the  alternating  current  is  supplied  to  the  field  in  .series  with  the 
armature,  so  that  when  the  direction  of  current  in  the  armature 


J-iO 


TIIK  S1.\(;LH-PIIASE  electric  ILMLWAV 


chano^os  it  also  reverses  in  the  Held.  Tlic  result  i^  tliat  llic  relative 
(lireetioii  of  current  in  tlu>  field  and  armature  is  constant  and  the 
motor  has,  therefore,  a  tendency  to  turn  eontinuouslv  in  ()n(^  direc- 
tion as  lon^  as  the  alternatin<:;-current  power  is  suj^plied. 

This  bein^"  (rue,  the  (piestion  may  arise  as  to  why  the  sin<jle- 
phase  motor  was  not  l)r()u^lit  to  the  front  for  railway  work  lon<^ 
ago.  'i'he  answer  is  that  there  were  certain  inherent  difficulties 
to  he  (nercome,  and  the  development  of  the  single-phase  motor 
has  been  simply  the  removal  of  these  difficulties,  rather  than  the 
design  of  an  entirely  new  type  of  macliine. 

The  most  serious  obstacle  to  overcome  is  the  sparking  at  the 
commutator,  (]uc  to  the  fact  that  when  the  terminals  of  a  coil  are 
bridged  by  a  brush,  the  coil  acts  like  the  short  circuited  secondary 
of  a  transformer  of  which  the  field  winding  constitutes  the  primary. 
Also  there  is  an  iron  loss  due  to  the  alternating  magnetic  flux  through 
the  magnetic  circuit;  wliile  another  objectionable  feature  is  the 
counter  E.^NI.F.  induced  in  the  field  coils. 


Alternating-Current    Kailwuj-  .Motor   I'iclil. 


In  order  that  it  may  overcome  these  difficulties,  to  some  extent, 
at  least,  the  single-phase  motor  presents  certain  modifications  from 
the  direct-current  type,  in  that  it  has  more  field  poles,  and  the  entire 
magnetic  circuit  of  field  frame,  cores,  and  pole  pieces,  is  carefully 
laminated.  The  number  of  conmiutator  segments  is  also  increased, 
thus  reducing  the  number  of  armature  turns  per  coil,  and  there 
are  special  features  introduced  to  prevent  sparking,  such  as  com- 
pensating  windings   which   neutralize   the   effect   of   armature   dis- 


THE  SIXGLK- PHASE  ELECTRIC  HAIEWAY 


U] 


Single-Phase  AYmature,  Unmounted. 


torti^^^'  the  use  of  narrow  brushes;  a  type  of  armature  win(lin<( 
whicli  gives  a  low  reactiinee  per  eoil;  the  use  of  W\(rh  resistance  leads 
between  the  armature  coils  and  commutator  segments,  etc. 

The  single-phase  motor  is  then  a  refined  and  highly  perfected 
type  of  direct-current  motor,  and  this  explains  the  fact  that  it  will 
operate  on  either  alternating-  or  direct-current  circuits.  In  fact 
some  claim  that  it  will  operate  even  more  efficient.y  on  direct  cur- 
rent than  th"  regulation  direct-current  motor  itself. 

The  field  for  which  the 
single-phase  motor  seems  par- 
ticularly adapted  is  that  of  heavy 
service  and  interurban  work, 
where  it  has  many  distinct  ad- 
vantages, among  which  may  be 
mentioned  the  following: 

The  alternating  current  on 
the  trolley  allows  the  use  of  a 
high  voltage  and  correspondingly 
smaller  current,  which  reduces 
the  line  loss  and  permits  of  the  use  of  smaller  wire,  which  of  course 
means  a  saving  in  the  investment  for  copper.  ]Moreover,  the  difficulty 
of  collecting  a  large  current  from  the  trolley  wire  is  overcome.  Rotary 
converter  substations  are  eliminated,  being  replaced  by  simple 
and  cheap  transformer  substations,  which  require  no  attendance. 
The  capacity  can  be  easily  increased  by  merely  increasing  the  num- 
ber of  these  transformer  substations. 

The  efficiency  of  speed  control  is  a  point  particularly  worthy 
of  mention.  In  direct-current  speed  control,  the  series-parallel 
method  is  used  almost  exclusively.  This  consists  of  putting  the 
motors  in  series  for  low  speed  and  in  parallel  for  high  speed.  This 
permits  of  two,  and  only  two,  economical  running  points;  the  one 
at  full  speed,  and  the  other  at  approximately  half  speed.  All  inter- 
mediate points  must  be  obtained  by  the  insertion  of  dead  resistance 
in  which  the  voltage  is  simply  wasted  as  heat,  thus  causing  a  large 
I0.SS  particularly  at  starting. 

With  the  single-phase  motor  the  current  is  supplied  to  the  car 
with  a  voltage  of  say  3300.  It  is  then  stepped  down  by  means  of 
transformers  on  the  car  to  the  voltage  of  the  motors,  which  may 


^42 


THE  SLNCiLK-rilASK  KI.KCTRIC  ILVILWAV 


be  200  or  2i')()  volts.  The  spocd  is,  of  fonrsc,  dcprndfrnt  upiii  tlio 
volta<i;e  aj^plicfl  to  tlu*  iiu)tors,  mikI  this  \()lta<i:c'  Is  cut  down  from 
the  maxiniiiin,  to  obtain  various  gradations,  by  means  of  an  indue- 
tion  controller,  or  by  taps  from  an  anto-transformer.  Thus  the 
motor  takes  from  tiie  trolley  only  slij^htly  more  power  than  is  actually 
recjuired  to  operate  it  at  any  ^iven  speed,  instead  of  takinn;  full 
volta<j;e  from  the  line  and  absorl)in(ij  part  of  it  in  dead  resistance. 
The  effect  of  electrolysis  upon  neighboring  water  pipes  par- 
allelin":  an  electric  road,  which  is  the  cause  of  so  much  troui)le  with 


Auto  Transfornior, 

direct  current,  is  entirely  eliminated,  as  electrolysis  evidently  will 
not  take  place  with  alternating  current. 

In  connection  with  this  svstem  a  sliding  contact  device  or  bow 
trolley  has  in  many  cases  been  substituted  with  considerable  success 
for  the  ordinary  current  collecting  device,  or  trf)lley  wheel,  one 
advantaii'e  of  this  Ix-ing  that  the  car  can  be  run  in  either  direction 
without  reversing  the  contact  device.  Another  verv  satisfactory 
form  of  trolley  is  of  the  pantograph  type  with  sliding  shoe,  shown 
on  the  New  York,  New  Haven  and  Hartford  locomotive. 

A  new  form  of  trolley  suspension  known  as  the  catenary  has 
betni  developed  to  meet  the  demand  for  more  substantial  construc- 
tion necessitated  by  the  high  trolley  voltage.  This  consists  of  a 
stranded  galvanized  steel  messenger  or  supporting  cable,  from 
which  the  trolley  wire  is  suspended  at  intervals  of  about  10  feet, 
tlius  keeping  it  at  a  uniform  distance  above  the  track. 


THE  SIXCU.E-PIIASE  ELECTRIC  RAILWAY 


ILJ 


The  inultipk'-iinit  system  of  control  can  be  used  in  connection 
with  single-phase  motors,  this  being  the  scheme  which  has  been  in 
use  for  a  long  time  on  elevated  and  other  roads  using  direct  current, 
whereby  several  cars  can  i)e  operated  in  a  train  from  a  single  jjoint, 
each  car  being  equipped  with  its  individual  motor  and  controlling- 
apparatus.  The  entire  system  is  then  controlled  as  one  unit  by  a 
single  motorman  stationed  usually  in  the  front  of  the  first  car.  This 
method  of  control  has  become  of  such 
tremendous  importance  that  any  sys- 
tem to  which  it  cannot  be  applied 
would  be  seriously  handicapped.  Cars 
equipped  with  single-phase  motors  can 
be  operated  on  either  direct-current  or 
alternating-current  lines,  with  high  or 
low  tension,  with  trolley  or  third  rail. 

It  must  not  be  supposed,  how- 
ever, that  with  all  the  above  mentioned 
advantages,  the  single-phase  system  has 
no  disadvantages,  as  such  is  not  the 
case.  The  car  etjuipment,  due  to  the 
transformers  and  the  nature  of  the 
motors,  is  considerablv  heavier.  The 
motors  themselves  are  more  expensive 
on  account  of  their  special  construc- 
tion. The  equipment  is  not  always 
adapted  for  operation  on  existing  lines. 
There  is  a  slight  increased  "apparent" 
resistance  of  the  trolley  line  and  a  con- 
siderable  increased  "apparent"  resist- 
ance oi  the  rails,  due  to  reactance 
caused  bv  the  alternatiiii!;  nature  of  the  current.  There  is  also  an 
active  electro-motive  force  between  the  field  coils,  which  is  objection- 
able, and  there  is  a  possibility  of  interference  with  neighboring  tele- 
phone lines.  Furthermore,  there  is  slight  loss  in  power  in  the 
transformers  on  the  car,  while  the  power-factor  of  the  motors  is  less 
than  unity. 

Summing  the  matter  up  as  a  whole,  liowcver,  the  advantages 
seem  to  overbalaiice  the  disadvantages,  at  least  for  many  kinds  of 


MasttT  <"oiilroller  Used  in  Comiec- 

lioii    with    the    MiiMiple-rnit 

System    as   AppHed    to 

Single-Phase  Work. 


144 


THE  SINGLE-PHASE  ELECTRIC  RAILWAY 


work,  and  it  is  safe  to  predict  that  this  new  system  of  operation  will 
have  a  very  wide  and  inereasin<i;  application  in  the  near  future. 

As  to  the  operation  of  the  system  in  general,  the  current  may 
be  developed  by  single-phase,  two-phase,  or  three-phase  generators, 
and  supplied  to  the  transformer  substations  just  as  it  was  formerly 
supplied  to  the  rotary  converter  substations.  Only  a  single  phase 
is  used  on  any  section  of  the  trolley  line.  The  voltage  on  this  trans- 
mission line  will  depend  upon  the  existing  conditions,  and  can  be 
figured  out  like  any  other  problem  in  power  transmission. 

Three-phase  generators  would  ordinarily  be  used,  as  less  copper 
is  recjuired  to  suj)ply  a  given  amount  of  ])ower.  The  common  fre- 
quency is  25  cycles  per  second.     At  the  transformer  stations,  the 


Truck  Comi)lete  with  Siugle-Phase  Motors  and  Contact  Shoes. 

voltage  is  then  stepped  down  to  that  required  on  the  tnjUey,  which 
may  be  2,000,  8,.3()(),  (^(lOO,  or  even  11,000  volts.  While  \ye  cannot 
speak  yet  of  a  standard  voltage,  3300  seems  to  be  finding  consider- 
able favor.  The  voltaire  for  which  the  motors  are  wound  is  200 
or  250,  the  General  Electric  motors  using  the  former  voltage,  and 
the  We.stinghou.se  the  latter.  When  o])erating  on  alternating  cur- 
rent the  motors  are  connected  in  parallel,  and  when  running  on 
direct  current  they  are  connected  in  .series.  ^Motors  have  been 
constructed  from  50  to  225  horse])ower,  and  there  is  no  apparent 
rea.son  why  larger  ones  c(juld  not  be  made  to  operate  with  ecjual 
sati.sfaction. 

Among  the  roads  in  this  country  which  arc  either  u.sing,  or 
planning  to  usv  single-])ha.se  current,  may  i)c  mentioned  the  Ballston- 
Scheneetady  line,  which  was  one  of  the  first  .sy.stems  to  be  ecjuipped 


THE  SIXCJI.E-PHASE  ELEClllIC  RAILWAY 


145 


Magnetic  Speed  Indicator. 


and  has  hcen  in  successful  operation  for  sonu-  time.  This  road 
uses  the  alternating-current  motor  developed  by  the  General  P^lec- 
tric  Co.  The  motors  are  adapted  for  operation  on  the  2,000-v()lt 
alternating-current  trolley  between  cities,  and  on  the  standard  GOO- 

volt  direct  current  in  Schenectady. 
They  are  wound  for  400  volts,  and  are 
operated  in  series  on  the  (iOO-volt  direct 
current.  The  frequency  used  is  25 
cycks.  Current  is  supplied  by  an 
overhead  trolley,  no  feeders  being  used. 
A  second  road  of  importance  is 
one  in  Georgia  between  Atlanta  and 
INIarietta,  which  is  15  miles  in  length. 
This  uses  the  Westinghouse  ec[uipment. 
The  current  on  the  trolley  is  2,200  volts 
and  25  cycles.  It  is  transmitted  at  a 
voltage  of  22,000. 

Another  road  of  importance  is  the 
Indiana!'  and  Cincinnati  interurban 
line,  41  miles  in  length,  which  has 
been  in  operation  on  regular  schedule  since  July  1st,  1905.  For  37 
miles  the  road  is  operated  from  alternating  current,  and  for  4  miles, 
from  direct  current.  Four  75-horse  power  motors  per  car  are  used, 
capable  of  a  maximum 
speed  of  05  miles  j)er  hour. 
The  Bloomington,  Pon- 
tiac  and  Joliet  Electric  Rail- 
way is  a  single-phase  road 
efpiipped  with  G(>ueral 
Electric  apparatus,  and  has 
maintained  a  regular  sched- 
ule over  a  distance  of  more 
than  10  miles  since  ]March, 
1005. 

The    j)lans     are     now 
being    laid     for    a     single- 
phase  road,  which  will  run  south  from  Spokane,  Washington,  a  dis- 
tance of  150  miles.     The  current  on  the  transmission  line  is  45,000 


Armature  Quill. 


140 


THE  SIXGLE-PIIASE  ELECTRIC  RAILWAY 


volts,  which  is  stej)po(l  down  to  (i.fiOO  on  thr  trolU-y.  The  car  will 
l>c  cajKihlc  ;)f  oj)cratint;-  on  cuircnt  from  a  (>,(K)()-V()lt  alternatinji;,  a 
700-volt  alternating,  or  a  oT.Vvolt  direct-current  supply. 

Perhaps  the  most  important  nunc  which  has  been  made  in  the 
direction  of  .sinf^le-phase  traction  thus  far  is  the  decision  of  the  New 
York,  New  Haven,  and  Hartford  road  to  estaUlish  a  long-distance 
passenger  traffic  on  the  single-phase  system.  According  to  the 
latest  plans  this  road  will  operate  hetween  the  (Irand  Central  Depot 
and  Woodlawn,  X.  W,  over  the  terminal  tracks  of  the  New  York 
Central  road,  on  direct  current  taken  from  the  trolley.     From  ^^'ood- 


A  Pair  of   l)ri\ti>   with  Sinjjle-Phuse  Molur  Mounted  iii)oii  (^uill. 


lawn,  X.  Y.,  to  Stamford,  Conn.,  the  road  will  he  operated  on  the 
single-phase  system. 

The  ecjuipment  is  being  sujjplied  by  the  Westinghouse  Co.  The 
current  is  generated  by  revolving-field  type  tiu'bine-driven  alter- 
nators. The  armatures  are  designed  for  either  three-pha.se  or  single- 
phase  connection.  The  current  is  generated  at  25  cycles  and  11,000 
volts,  being  delivered  directly  to  the  trolley,  and  thence  to  the  cars, 
without  the  intervention  of  anv  transformers.  The  double  catenarv 
suspension  from  messenger  wires  is  used  to  support  the  trolley. 
The  locomotives  are  each  ecjuipped  with  foin-  200-H.  P.  gearless 
motors,  designed  to  operate  on  2oo-volt  alternating  current  and 
275-  to  300-volt  tlirect  current. 


THE  SINGLE-PHASE  ELECTRIC  KAH.WAY 


147 


'Vhv  anuaturc  is  not  inountcHl  on  tin-  .shaft  direct,  l)Ut  is  built 
ii})()ii  a  ({uill  tlir()u<i;h  which  the  axle  passes  witli  about  Ij-inch  clear- 
ance all  around.  There  is  a  flange  at  each  end  of  the  quill  from 
which  seven  pins  project  and  fit  into  the  hubs  of  the  driving  wheels. 
( )n  the  direct-current  part  of  the  line,  current  is  tlelivcrcd  to  the  car 
through  eight  collecting  shoes  from  a  third  rail.  On  the  alternating- 
current  section,  current  is  delivered  through  two  pantograph  bow 
trolleys.  On  the  direct-current  section  the  series-parallel  method 
of  speed  control  is  used,  current  being  fed  directly  to  the  motors 
ivhich  are  connected  two  in  series  permanently  and  the  series-parallel 
control  is  applied  to  the  motors  in  groups  of  two.  The  alternating- 
current  speed  control  is  accomplished  by  six  taps  from  an  auto- 
transformer  for  the  corresponding  running  points.     The  cars  weigh 


Six-Unit  Switch  Group,  Siugle-Piiase  System. 

7S  tons  and  are  capable  of  a  speed  of  00  to  05  miles  per  hour.  The 
electro-pneumatic  unit-switch  type  of  control  is  used.  At  each  end 
of  the  cab  is  a  master  controller  from  which  the  main  controller  is 
operated.  Several  locomotives  can  be  operated  together  on  the 
multiple-unit  system,  if  desired. 

'i'lie  Washington,  Baltimore  and  Indiana  single-phase  road  is 
the  latest  in  the  field,  contracts  having  been  placed  very  recentlv. 
The  current  will  be  transmitted  at  33,000  volts  and  25  evcles,  then 
being  stepped  down  to  0,000  volts  on  the  trolley.  The  road  will  be 
00  miles  long  and  will  be  equipped  with  (reneral  Electric  apparatus. 
Four  125-H.  P.  motors  capable  of  operating  on  either  alternating 
current  or  direct  current  will  bi'  used,  and  the  cars  will  be  capable 
of  a  speed  of  00  miles  per  hour. 


INDEX 

/  

Page 

Air  brakes 56 

Air  compressors 57 

automatic  ocovornor  for 57 

Wcstinghouse 5S 

Alternating-current  generators 105 

Alternating-current  switchboards. 110 

Altermiting-current  systems 113 

single-phase  motors 114 

three-phase  motors 113 

Alternating-current  transmission 99 

Amiature  coils S 

Armature  leads 9 

Armature  tests  for  grounds 1 33 

Armature  winding 5 

defects  of. ,. 1 24 

mistakes  in 120 

Automatic  governor  for  air  compressors 57 

Ballast ■ S5 

Bearings  of  railwaj'^  motors 13 

Block  signals  for  electric  railwaj's 94 

Bond  testing 120 

Bonding  and  return  circuits 88 

Booster  feeder 98 

Brackets 75 

Brake  leverages  and  shoe  pressure 54 

Brake  rigging 53 

Brake  shoes 64 

Brusii  h'olders 10 

Brushes 10 

Burn-outs 123 

.Canopy  switch 39 

Car,  failure  of  to  start 1 27 

Car  bodies 67 

Car  circuit  breaker 39 

Car  const  ruction 67 

Car  equipment 3 

Car  heaters 34 

electric 34 

hot-water 36 

Car  painting 72 

Car  repair  sho|)s 134 


150  INDEX 

Pape 

Car  weights 72 

Car  wheels.  . •'il 

Car  wiriiii: 37 

Cast-wc'lilcd  joints S7 

Coefficient  of  f rict  ion 65 

Common  T-rail 84 

Commutator  type  single-piiase  motor 139 

Compressors ». 57 

Conductivity  of  steel  rail 80 

Conduit  systems •. 81 

contact  plow 82 

cost  of •■ 82 

current  leakage 83 

Contact  plow 82 

Contact  shoes 45 

Controller  construction 19 

Controller  notches 27 

Controller  wirinii 2(1 

Cont  rollers Hi 

Cost  of  power •• 119 

Couplers GO 

Current  required  to  heat  cars 35 

Current  leakage •. 83 

Defects  of  armature  windings 124 

Direct -current  feeding 98 

Double-current  generators 105 

Drawbars (Hi 

Economy  in  power 118 

Electric  car  accessories : 39 

canoi)y  switch 39 

car  circuit  breaker 39 

contact  shoes 45 

fuses 41 

lamp  circuits 43 

lightning  arresters 41 

trolley  base. M 

t  rolley  poles 44 

trolley  harp 45 . 

trolley  wheels 44 

Electric  cars,  road  tests  of 117 

Electric  heaters  for  cars 34 

Electric  railway 1 

Electrically  welded  joints 87 

Electrolysis 95 

prevention  of 97 

Feeder  panel • 110 

Feeder  systems 92 

Feeders 75 


INDEX  ir,i 

Papo 

Field  roils "^ 

Fiekl  tosts  for  grounds 133 

Four  motors 10 

Fuse  blows 1 30 

Fuses • 41 

Gearino; 12 

O.  E.  electric  brake 01 

G.  E.  train  control « 20 

Generator,  startinjj  up lOS 

Generator  D.  ('.  jianels 100 

Generators. 10.") 

Girder  rail 83 

Grounds 1 23 

High-tension  lines 77 

High-tension  oil  switches Ill 

Highway  crossings NO 

Hot -water  heaters  for  cars 30 

Insulators,  tiiird  rail ■■ 70 

Interurban  railway,  system  of  distribution  for 101 

Joints  for  rails ' 80 

Lamp  circuits 43 

Lightning  arresters 41 

Locating  defects  in  motor  and  controller  wiring 128 

Location  of 

power  houses 101 

third  rail 79 

Lubrication  of  raihvay  motors 13 

Magnetic  blow- -out 2G 

Maximum  traction  trucks 51 

Momentum  brakes 59 

Motor  leads 9 

Motor  suspension 14 

Motor-coil  te.sting 121 

Mot  ors 3 

as  emergency  brakes 03 

of  the  New  York  Central  electric  locomotive 15 

Multiple-unit  control 29 

Oil  switches,  high  tension Ill 

Open-circuit  tests 1 28 

Opening  cases  for  inspection 10 

Overhead  construction 73 

brackets 75 

feeders 75 

high-tension  lines 77 

section  insulators 70 

span  wires 74 

trolley  wire 73 

trolley-wire  clamps  and  ears 73 


i:>L'  INDEX 

PufTO 

Potter  third-rail  shoo \i\ 

Power 

cost  of 119 

economy  in 1 1  ,S 

taken  by  cars 115 

Power  house  location 101 

Power  stations,  general  jilan  of 105 

Power  supply  and  distribution OS 

Railway  motors 

bearings 13 

brushes 10 

characterisics  of 3 

gearing  of ." 12 

lubrication  of 13 

Rate  of  retardation  in  l)raking 00 

Resistance  of  t  rack 91 

Resistances 38 

Return  feeders 92 

Reversal  of  motor 20 

Reversed  fields 1 33 

Rheostat  control 17 

Road  tests  of  electric  cars 117 

Sectional  insulators 70 

Series-parallel  control 17 

Shanghai  T-rail 84 

Short-circuit  tests 1 30 

Single  trucks 48 

Single-phase  electric  railway 130 

Single-phase  motors 114,139 

Sleet  on  trolleys  and  third  rails 40 

Sliding  and  spinning  wheels 119 

Span  wires 74 

Sparking  at  the  commutator 1 27 

Sprague  mutliple-unit  system  of  control 29 

Steel  car  framing 71 

Storage  air  V)rakes 58 

Storage  batteries  in  stations 113 

Street  railway  motors,  general  data  on 0 

Supplementary  return  feeders 92 

Swing  bolster  trucks 49 

Switchboards 1 00 

alternating-current 110 

Switches,  third  rail 79 

Swivel  trucks 48 

T-rail    •  84 

Thermit  welding 88 

Third  rail 79 

advantages  in  operation 80 


INDEX  i:,3 

. - -■ i__ 

Page 
Third  rail 

"comluptivity  of SO 

cost  of SO 

higliway  crossings SO 

insulators  for 79 

location 79 

switches 79 

Tliroc-pliasc  motors 11;^ 

Track  brakes.. ()3 

Track  construction S3 

Track  resistance 91 

Track  sandcrs. . 05 

Track  support S5 

Transmission  systems,  efficiency  of 101 

Trilby  groove  rail S4 

Trolley  ba.se 44 

Trolley  harp 45 

Trolley  poles 44 

Trolley  wheeli^ 44 

'I  I'olley  wire ' 73 

Trolley-wire  clamps  and  cars 73 

Trucks • ' 10 

maximum  fraction 51 

single ''^ 

swing  bolster.. 49 

swivel 4S 

Type  L  controllers,  wiring  of 24 


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